Belt Printer Updates - Oct 4 (#16127 )

# Belt Printing Bug Fixes & Feature Updates This should be the majority of substantive work keeping ``belt-printer`` from being ready to merge into ``main``. It includes Hanif Koh's review fixes from #15685 and the answers to his review on #14394, findings from running the branch on a BabyBelt Pro and an IR3 V2, crash fixes contributed by Unlayered3D, and arrange and purge-tower changes for multi-colour belt prints. The merge of current `main` into this branch is prepared and tested locally. The conflicts are in the acceleration refactor of `GCode::_extrude`, the ClipperLib namespace clean-up and a few test files. Tested with `libslic3r_tests`, `fff_print_tests` and `libnest2d_tests` on Linux, validated on a stock Klipper BabyBelt Pro. ## New features **Belt arrangement.** Parts of the same colour are grouped along the belt into a single print run. Packing starts at the end that prints first, following the slicing rotation and the sign of the angle. Arrange reserves the purge prism's strip and the brim width along the bed edges, then regenerates the prism from the result instead of moving it as a part. Piles aimed at an off-centre `best_object_pos` are clamped to the bed. Grouping uses a soft cost: if the belt is too short for separate runs, colours overlap rather than move to another plate. **Purge tower sizing.** The prism stops at the plate end. The purge planner's existing warning reports what a shortened bar can't absorb. A brim is accepted next to the purge tower again because the purge plan's layer-grid shift now also moves the brim's apron bands. **First-layer fan band.** On a belt, "the first layers" are a band along the belt rather than the first slicing layers. The generator marks where each extrusion enters and leaves the band. The cooling buffer keeps the fan off inside it on every layer, taking precedence over overhang and bridge fan requests. Thanks to: @Unlayered3D, @shubhracc, @dlc60, @Rexit **Profiles.** Z-hop defaults to 0 on belt printer bases and belt filaments; it can be turned back on. Axis remap options are shown only in Develop mode. IdeaFormer, Printcepts and Custom bundle versions are bumped. Thanks to: @RobMink, @Rexit ## Bug fixes - Scarf joint seams no longer start below the layer on a belt. Previously, each seam caused a 0.28 mm belt back-step into the previous layer ("the belt jumped backwards and the head hit the part"). — credit: @dlc60 - The CLI no longer rejects every belt print with -102. The printable-height check compared machine Z, which is belt travel on a belt printer. - The belt header is written outside the optional file header block, so printers with a BTT TFT thumbnail still get belt view in the preview. — credit: BabyBelt Discord - The dormant tilted-bed rendering is removed from Prepare view; the bed is shown as the slicing pipeline treats it. — credit: HanifKoh - Plate icons, number and name no longer run across the neighbouring plate on a long, narrow bed; their scale is bounded by the gap between plates. - Modifiers and support blockers no longer extend a belt object's sliced range. The `is_model_part` filter had gone missing with some debug logging. — credit: HanifKoh - Crossing-perimeter avoidance no longer dereferences a null layer in either pass while travelling on a brim apron layer. — credit: Unlayered3D - 3MF files with non-finite vertex coordinates are rejected instead of crashing qhull during load. — credit: Unlayered3D - The CLI no longer crashes on a project without `printable_height` or with fewer filaments than were loaded. — credit: Unlayered3D - The island tour cache is keyed on the island layout, preventing out-of-bounds reads on later layers with fewer islands. — credit: Unlayered3D - The top/bottom painting projection no longer erases from an empty vector when no shell layers are requested. — credit: Unlayered3D - Belt purge planning detects filament changes by scanning the tool ordering instead of checking the first layer's flag, which a brim apron layer never carries. — credit: Unlayered3D - The purge prism never gets a brim, regardless of its config. — credit: Unlayered3D - Containment tests treat the plate as open along Y on an infinite-Y belt printer. — credit: Unlayered3D - Belt brim lattice lines close to the belt move uphill; narrow bands no longer get near-duplicate lines. - Organic supports that reach the belt slice without negative flow. - Hanif Koh's review items: restored the gantry clearance check in `Print::validate`, read the pre-slice remap header at its real length, removed unused `clip_support_fills()` and the two unimplemented support floor modes (legacy values map to `none`), dropped the per-extrusion transform determinant, indexed apron layers into the first layer's nozzle map, read the brim axis from the config, removed tagged diagnostic logging and planning-doc references, and documented the exclude-object frame. — credit: Hanif Koh - Hanif Koh's fixes from #15685 include the plate offset in the belt writer, painted supports and seams under the belt transform, shared build-plate tilt helpers, the belt header as the source of the tilt, brim band loop and filament, and G-code export invalidation. — credit: hanifkoh At this time there are no known issues with belt printing nor any known regressions in non-belt-printing execution paths. I have been using these builds for all of my printing for several months now and have had no issues.
Preview: judge a belt print's toolpaths by their back-transformed box
2026-10-04 22:31:02 +00:00 · 2026-10-04 11:29:42 -05:00 · 2026-10-03 19:19:02 -05:00 · 2026-10-03 18:59:01 -05:00 · 2026-10-03 15:39:49 -05:00 · 2026-10-03 13:12:41 -05:00
159 changed files with 12950 additions and 637 deletions
@@ -1111,7 +1111,27 @@ private:
        default: ; // DONT_ALIGN
        }

-        auto d = cb - ci;       
+        auto d = cb - ci;
+
+        // Keep the pile on the bin. A target near an edge (a belt printer starts its parts
+        // at the leading end of the belt) would otherwise centre a pile that is larger than
+        // the room around that point on it and push part of the pile off the bed. The pile
+        // stops at the edge instead; the items' boxes carry their inflation, which is the
+        // margin left there. A pile that does not fit along an axis is centred on it.
+        {
+            auto on_bin = [](Coord lo, Coord hi, Coord bin_lo, Coord bin_hi, Coord shift) {
+                if (hi - lo >= bin_hi - bin_lo)
+                    return (bin_lo + bin_hi) / 2 - (lo + hi) / 2;
+                if (lo + shift < bin_lo)
+                    shift = bin_lo - lo;
+                if (hi + shift > bin_hi)
+                    shift = bin_hi - hi;
+                return shift;
+            };
+            setX(d, on_bin(getX(bb.minCorner()), getX(bb.maxCorner()), getX(bbin.minCorner()), getX(bbin.maxCorner()), getX(d)));
+            setY(d, on_bin(getY(bb.minCorner()), getY(bb.maxCorner()), getY(bbin.minCorner()), getY(bbin.maxCorner()), getY(d)));
+            cb = ci + d;
+        }

        // BBS make sure the item won't clash with excluded regions
        // do we have wipe tower after arranging?
@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+"""Belt temperature-tower asset generator (discrete-provini design).
+
+A vertical temperature tower cannot be sliced on a belt printer, so lay a row of
+DISCRETE provini (one per temperature) along the belt (designed Y) with a fixed
+surface gap. Each provino is the chevron+arc unit (belt_temp_provino_unit.stl,
+keel-first); its temperature is ENGRAVED upright into the 50 mm face — a raised
+number would be an unsupported overhang on the belt. The C++ calib_temp belt branch
+(Plater.cpp) injects one M104 per zone 70 layers INTO provino i:
+  print_z[i] = i * PITCH * cos(theta) + 70 * layer_height   (theta = 45)
+inside the body, not in the empty inter-provino gap (which has no sliced layers for
+the event to attach to). PITCH below is the shared geometry contract with that code —
+keep them in sync.
+
+Generates one STL per filament temp range used by Temp_Calibration_Dlg.
+"""
+import numpy as np, trimesh, os
+from matplotlib.textpath import TextPath
+from matplotlib.font_manager import FontProperties
+from shapely.geometry import Polygon as ShPoly
+from shapely.ops import unary_union
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+UNIT = os.path.join(HERE, 'belt_temp_provino_unit.stl')   # single provino, keel-first
+SURF_GAP = 25.0            # surface-to-surface gap between provini (mm) — user spec
+TEXT_H = 9.0
+TEXT_DEPTH = 0.8           # engraving depth (numbers are CUT into the face, not raised:
+                          # a raised number is an unsupported Y-overhang on the belt)
+TEXT_OVERSHOOT = 0.6       # extra height poking out of the face for a clean boolean cut
+
+# Temperature ranges (start, end) per filament family, 5 C step. File name encodes them.
+RANGES = [(230,190),(270,230),(250,230),(280,240),(240,210),(320,280)]
+
+unit = trimesh.load(UNIT)
+dY = unit.bounds[1,1] - unit.bounds[0,1]
+PITCH = dY + SURF_GAP                       # designed-Y pitch == C++ contract constant
+print(f"unit dY={dY:.2f}  PITCH={PITCH:.3f}  (C++ contract: print_z[i]=i*{PITCH:.3f}*cos45)")
+
+# 50 mm face normal (0,-1,1)/sqrt2 ; UPRIGHT basis u=+X det(+1) (verified non-mirrored)
+n = np.array([0,-1,1.])/np.sqrt(2)
+u = np.array([1,0,0.]); v = np.array([0,1,1.])/np.sqrt(2)
+R = np.column_stack([u,v,n])
+fn = unit.face_normals; fc = unit.triangles_center; fa = unit.area_faces
+sel = (fn@n) > 0.9
+face_c = (fc[sel]*fa[sel,None]).sum(0)/fa[sel].sum()
+
+def text_mesh(s):
+    tp = TextPath((0,0), s, size=TEXT_H, prop=FontProperties(family='DejaVu Sans'))
+    rings = [ShPoly(p) for p in tp.to_polygons() if len(p)>=3]
+    rings.sort(key=lambda r:r.area, reverse=True)
+    used=[False]*len(rings); parts=[]
+    for i,o in enumerate(rings):
+        if used[i]: continue
+        holes=[]
+        for j in range(i+1,len(rings)):
+            if not used[j] and o.contains(rings[j]): holes.append(rings[j].exterior.coords); used[j]=True
+        parts.append(ShPoly(o.exterior.coords,holes)); used[i]=True
+    poly = unary_union(parts)
+    geoms = list(poly.geoms) if poly.geom_type=='MultiPolygon' else [poly]
+    m = trimesh.util.concatenate([trimesh.creation.extrude_polygon(g,height=TEXT_DEPTH+TEXT_OVERSHOOT) for g in geoms])
+    c = m.bounds.mean(axis=0); m.apply_translation([-c[0],-c[1],0]); return m
+
+for t_start, t_end in RANGES:
+    temps = list(range(t_start, t_end-1, -5))
+    parts=[]
+    for i,T in enumerate(temps):
+        c = unit.copy(); c.apply_translation([0, i*PITCH, 0])
+        t = text_mesh(str(T)); M=np.eye(4); M[:3,:3]=R; t.apply_transform(M)
+        # place the text spanning from TEXT_DEPTH inside the face to TEXT_OVERSHOOT outside,
+        # then CUT it out of the provino (engrave) — no raised material, no Y-overhang.
+        t.apply_translation(face_c - n*TEXT_DEPTH + np.array([0,i*PITCH,0]))
+        c = trimesh.boolean.difference([c, t], engine='manifold')
+        parts.append(c)
+    asset = trimesh.util.concatenate(parts)
+    out = os.path.join(HERE, f"belt_temp_tower_{t_start}_{t_end}.stl")
+    asset.export(out)
+    dims = np.round(asset.bounds[1]-asset.bounds[0],1)
+    wt = all(p.is_watertight for p in parts)
+    print(f"  {t_start}->{t_end}: {len(temps)} zones  bbox={dims}  watertight={wt}  -> {os.path.basename(out)}")
@@ -1,9 +1,13 @@
 {
 	"name": "Custom Printer",
-	"version": "02.04.00.04",
+	"version": "02.04.00.06",
 	"force_update": "0",
 	"description": "My configurations",
 	"machine_model_list": [
+		{
+			"name": "Generic Belt Printer",
+			"sub_path": "machine/MyBeltPrinter.json"
+		},
 		{
 			"name": "Generic Klipper Printer",
 			"sub_path": "machine/MyKlipper.json"
@@ -62,6 +66,14 @@
 			"name": "0.16mm Optimal @MyKlipper",
 			"sub_path": "process/0.16mm Optimal @MyKlipper.json"
 		},
+		{
+			"name": "0.12mm Fine @MyBeltPrinter",
+			"sub_path": "process/0.12mm Fine @MyBeltPrinter.json"
+		},
+		{
+			"name": "0.20mm Standard @MyBeltPrinter",
+			"sub_path": "process/0.20mm Standard @MyBeltPrinter.json"
+		},
 		{
 			"name": "0.20mm Standard @MyKlipper",
 			"sub_path": "process/0.20mm Standard @MyKlipper.json"
@@ -262,18 +274,38 @@
 			"name": "MyKlipper 0.8 nozzle",
 			"sub_path": "machine/MyKlipper 0.8 nozzle.json"
 		},
+		{
+			"name": "fdm_belt_common",
+			"sub_path": "machine/fdm_belt_common.json"
+		},
 		{
 			"name": "fdm_toolchanger_common",
 			"sub_path": "machine/fdm_toolchanger_common.json"
 		},
-		{
-			"name": "MyRepetier 0.4 nozzle",
-			"sub_path": "machine/MyRepetier 0.4 nozzle.json"
-		},
 		{
 			"name": "MyRRF 0.4 nozzle",
 			"sub_path": "machine/MyRRF 0.4 nozzle.json"
 		},
+		{
+			"name": "MyBeltPrinter 0.2 nozzle",
+			"sub_path": "machine/MyBeltPrinter 0.2 nozzle.json"
+		},
+		{
+			"name": "MyBeltPrinter 0.4 nozzle",
+			"sub_path": "machine/MyBeltPrinter 0.4 nozzle.json"
+		},
+		{
+			"name": "MyBeltPrinter 0.6 nozzle",
+			"sub_path": "machine/MyBeltPrinter 0.6 nozzle.json"
+		},
+		{
+			"name": "MyBeltPrinter 0.8 nozzle",
+			"sub_path": "machine/MyBeltPrinter 0.8 nozzle.json"
+		},
+		{
+			"name": "MyRepetier 0.4 nozzle",
+			"sub_path": "machine/MyRepetier 0.4 nozzle.json"
+		},
 		{
 			"name": "MyToolChanger 0.2 nozzle",
 			"sub_path": "machine/MyToolChanger 0.2 nozzle.json"
@@ -0,0 +1,27 @@
+{
+	"type": "machine",
+	"name": "MyBeltPrinter 0.2 nozzle",
+	"inherits": "fdm_belt_common",
+	"from": "system",
+	"setting_id": "3w1uyJdmm14QhDnH",
+	"instantiation": "true",
+	"printer_model": "Generic Belt Printer",
+	"default_print_profile": "0.12mm Fine @MyBeltPrinter",
+	"nozzle_diameter": [
+		"0.2"
+	],
+	"max_layer_height": [
+		"0.16"
+	],
+	"min_layer_height": [
+		"0.04"
+	],
+	"printer_variant": "0.2",
+	"printable_area": [
+		"0x0",
+		"350x0",
+		"350x350",
+		"0x350"
+	],
+	"printable_height": "300"
+}
@@ -0,0 +1,20 @@
+{
+	"type": "machine",
+	"name": "MyBeltPrinter 0.4 nozzle",
+	"inherits": "fdm_belt_common",
+	"from": "system",
+	"setting_id": "6nRHUtvJOUffocbu",
+	"instantiation": "true",
+	"printer_model": "Generic Belt Printer",
+	"nozzle_diameter": [
+		"0.4"
+	],
+	"printer_variant": "0.4",
+	"printable_area": [
+		"0x0",
+		"350x0",
+		"350x350",
+		"0x350"
+	],
+	"printable_height": "300"
+}
@@ -0,0 +1,26 @@
+{
+	"type": "machine",
+	"name": "MyBeltPrinter 0.6 nozzle",
+	"inherits": "fdm_belt_common",
+	"from": "system",
+	"setting_id": "K0m9HbUNwKT4UCJV",
+	"instantiation": "true",
+	"printer_model": "Generic Belt Printer",
+	"nozzle_diameter": [
+		"0.6"
+	],
+	"max_layer_height": [
+		"0.4"
+	],
+	"min_layer_height": [
+		"0.12"
+	],
+	"printer_variant": "0.6",
+	"printable_area": [
+		"0x0",
+		"350x0",
+		"350x350",
+		"0x350"
+	],
+	"printable_height": "300"
+}
@@ -0,0 +1,26 @@
+{
+	"type": "machine",
+	"name": "MyBeltPrinter 0.8 nozzle",
+	"inherits": "fdm_belt_common",
+	"from": "system",
+	"setting_id": "rHAweDz4eNwttPNA",
+	"instantiation": "true",
+	"printer_model": "Generic Belt Printer",
+	"nozzle_diameter": [
+		"0.8"
+	],
+	"max_layer_height": [
+		"0.6"
+	],
+	"min_layer_height": [
+		"0.2"
+	],
+	"printer_variant": "0.8",
+	"printable_area": [
+		"0x0",
+		"350x0",
+		"350x350",
+		"0x350"
+	],
+	"printable_height": "300"
+}
@@ -0,0 +1,12 @@
+{
+	"type": "machine_model",
+	"name": "Generic Belt Printer",
+	"model_id": "my_belt_01",
+	"nozzle_diameter": "0.4;0.2;0.6;0.8",
+	"machine_tech": "FFF",
+	"family": "MyPrinter",
+	"bed_model": "Custom_350_bed.stl",
+	"bed_texture": "orcaslicer_bed_texture.svg",
+	"hotend_model": "",
+	"default_materials": "Generic PLA @System;Generic PLA-CF @System;Generic PETG @System;Generic TPU @System;Generic PC @System;Generic PVA @System;Generic PA @System;Generic PA-CF @System"
+}
@@ -0,0 +1,99 @@
+{
+	"type": "machine",
+	"name": "fdm_belt_common",
+	"inherits": "fdm_klipper_common",
+	"from": "system",
+	"instantiation": "false",
+	"gcode_flavor": "klipper",
+	"single_extruder_multi_material": "0",
+	"default_filament_profile": [
+		"Generic PLA @System"
+	],
+	"default_print_profile": "0.20mm Standard @MyBeltPrinter",
+	"max_layer_height": [
+		"0.32"
+	],
+	"min_layer_height": [
+		"0.08"
+	],
+	"deretraction_speed": [
+		"30"
+	],
+	"extruder_colour": [
+		"#FCE94F"
+	],
+	"extruder_offset": [
+		"0x0"
+	],
+	"long_retractions_when_cut": [
+		"0"
+	],
+	"nozzle_diameter": [
+		"0.4"
+	],
+	"retract_before_wipe": [
+		"70%"
+	],
+	"retract_length_toolchange": [
+		"2"
+	],
+	"retract_lift_above": [
+		"0"
+	],
+	"retract_lift_below": [
+		"0"
+	],
+	"retract_lift_enforce": [
+		"All Surfaces"
+	],
+	"retract_restart_extra": [
+		"0"
+	],
+	"retract_restart_extra_toolchange": [
+		"0"
+	],
+	"retract_when_changing_layer": [
+		"1"
+	],
+	"retraction_distances_when_cut": [
+		"18"
+	],
+	"retraction_length": [
+		"0.8"
+	],
+	"retraction_minimum_travel": [
+		"1"
+	],
+	"retraction_speed": [
+		"30"
+	],
+	"travel_slope": [
+		"3"
+	],
+	"wipe": [
+		"1"
+	],
+	"wipe_distance": [
+		"1"
+	],
+	"z_hop": [
+		"0"
+	],
+	"z_hop_types": [
+		"Normal Lift"
+	],
+	"gcode_remap_x": "rev_x",
+	"gcode_remap_y": "pos_z",
+	"gcode_remap_z": "pos_y",
+	"printer_extruder_id": [
+		"1"
+	],
+	"belt_printer": "1",
+	"belt_slice_rotation": "x",
+	"belt_slice_rotation_angle": "45",
+	"belt_slice_rotation_global": "1",
+	"build_plate_tilt_x": "45",
+	"purge_in_prime_tower": "0",
+	"scan_first_layer": "0",
+	"auxiliary_fan": "0"
+}
@@ -0,0 +1,20 @@
+{
+	"type": "process",
+	"name": "0.12mm Fine @MyBeltPrinter",
+	"inherits": "fdm_process_klipper_common",
+	"from": "system",
+	"setting_id": "EugqqdLJ423bgEwN",
+	"instantiation": "true",
+	"layer_height": "0.12",
+	"initial_layer_print_height": "0.12",
+	"bottom_shell_layers": "5",
+	"top_shell_layers": "6",
+	"support_top_z_distance": "0.08",
+	"support_bottom_z_distance": "0.08",
+	"skirt_loops": "0",
+	"skirt_distance": "0",
+	"compatible_printers": [
+		"MyBeltPrinter 0.2 nozzle",
+		"MyBeltPrinter 0.4 nozzle"
+	]
+}
@@ -0,0 +1,17 @@
+{
+	"type": "process",
+	"name": "0.20mm Standard @MyBeltPrinter",
+	"inherits": "fdm_process_klipper_common",
+	"from": "system",
+	"setting_id": "YzCDAgH3uLOM53pF",
+	"instantiation": "true",
+	"layer_height": "0.2",
+	"initial_layer_print_height": "0.2",
+	"skirt_loops": "0",
+	"skirt_distance": "0",
+	"compatible_printers": [
+		"MyBeltPrinter 0.4 nozzle",
+		"MyBeltPrinter 0.6 nozzle",
+		"MyBeltPrinter 0.8 nozzle"
+	]
+}
@@ -0,0 +1,54 @@
+{
+    "name": "IdeaFormer",
+    "version": "02.00.00.05",
+    "force_update": "0",
+    "description": "IdeaFormer belt printer configurations",
+    "machine_model_list": [
+        {
+            "name": "IdeaFormer IR3 V2",
+            "sub_path": "machine/IdeaFormer IR3 V2.json"
+        }
+    ],
+    "process_list": [
+        {
+            "name": "fdm_process_common",
+            "sub_path": "process/fdm_process_common.json"
+        },
+        {
+            "name": "0.20mm Standard @IdeaFormer IR3 V2",
+            "sub_path": "process/0.20mm Standard @IdeaFormer IR3 V2.json"
+        }
+    ],
+    "filament_list": [
+        {
+            "name": "Generic PLA @IdeaFormer IR3 V2",
+            "sub_path": "filament/Generic PLA @IdeaFormer IR3 V2.json"
+        },
+        {
+            "name": "eSUN PLA @IdeaFormer IR3 V2",
+            "sub_path": "filament/eSUN PLA @IdeaFormer IR3 V2.json"
+        },
+        {
+            "name": "Generic PETG @IdeaFormer IR3 V2",
+            "sub_path": "filament/Generic PETG @IdeaFormer IR3 V2.json"
+        }
+    ],
+    "machine_list": [
+        {
+            "name": "fdm_machine_common",
+            "sub_path": "machine/fdm_machine_common.json"
+        },
+        {
+            "name": "fdm_klipper_common",
+            "sub_path": "machine/fdm_klipper_common.json"
+        },
+        {
+            "name": "fdm_belt_common",
+            "sub_path": "machine/fdm_belt_common.json"
+        },
+        {
+            "name": "IdeaFormer IR3 V2 0.4 nozzle",
+            "sub_path": "machine/IdeaFormer IR3 V2 0.4 nozzle.json"
+        }
+    ]
+}
@@ -0,0 +1,110 @@
+{
+	"type": "filament",
+	"name": "Generic PETG @IdeaFormer IR3 V2",
+	"inherits": "Generic PETG @System",
+	"from": "system",
+	"setting_id": "n4zaXcUUzTqAxq5f",
+	"instantiation": "true",
+	"compatible_printers": [
+		"IdeaFormer IR3 V2 0.4 nozzle"
+	],
+	"filament_type": [
+		"PETG"
+	],
+	"filament_vendor": [
+		"Generic"
+	],
+	"filament_settings_id": [
+		"Generic PETG @IdeaFormer IR3 V2"
+	],
+	"filament_diameter": [
+		"1.75"
+	],
+	"filament_density": [
+		"1.27"
+	],
+	"filament_flow_ratio": [
+		"0.95"
+	],
+	"filament_cost": [
+		"25"
+	],
+	"filament_max_volumetric_speed": [
+		"10"
+	],
+	"nozzle_temperature": [
+		"240"
+	],
+	"nozzle_temperature_initial_layer": [
+		"245"
+	],
+	"nozzle_temperature_range_low": [
+		"220"
+	],
+	"nozzle_temperature_range_high": [
+		"260"
+	],
+	"temperature_vitrification": [
+		"70"
+	],
+	"hot_plate_temp": [
+		"80"
+	],
+	"hot_plate_temp_initial_layer": [
+		"80"
+	],
+	"cool_plate_temp": [
+		"80"
+	],
+	"cool_plate_temp_initial_layer": [
+		"80"
+	],
+	"textured_plate_temp": [
+		"80"
+	],
+	"textured_plate_temp_initial_layer": [
+		"80"
+	],
+	"fan_min_speed": [
+		"40"
+	],
+	"fan_max_speed": [
+		"60"
+	],
+	"overhang_fan_threshold": [
+		"25%"
+	],
+	"overhang_fan_speed": [
+		"80"
+	],
+	"close_fan_the_first_x_layers": [
+		"3"
+	],
+	"full_fan_speed_layer": [
+		"8"
+	],
+	"slow_down_min_speed": [
+		"20"
+	],
+	"slow_down_layer_time": [
+		"4"
+	],
+	"fan_cooling_layer_time": [
+		"100"
+	],
+	"reduce_fan_stop_start_freq": [
+		"1"
+	],
+	"filament_retraction_length": [
+		"2"
+	],
+	"filament_retraction_speed": [
+		"40"
+	],
+	"filament_deretraction_speed": [
+		"40"
+	],
+	"filament_start_gcode": [
+		"; Generic PETG @IdeaFormer IR3 V2 — belt PETG, bed 80C"
+	]
+}
@@ -0,0 +1,110 @@
+{
+	"type": "filament",
+	"name": "Generic PLA @IdeaFormer IR3 V2",
+	"inherits": "Generic PLA @System",
+	"from": "system",
+	"setting_id": "1xjycsEAFh6KQIhp",
+	"instantiation": "true",
+	"compatible_printers": [
+		"IdeaFormer IR3 V2 0.4 nozzle"
+	],
+	"filament_type": [
+		"PLA"
+	],
+	"filament_vendor": [
+		"Generic"
+	],
+	"filament_settings_id": [
+		"Generic PLA @IdeaFormer IR3 V2"
+	],
+	"filament_diameter": [
+		"1.75"
+	],
+	"filament_density": [
+		"1.24"
+	],
+	"filament_flow_ratio": [
+		"0.98"
+	],
+	"filament_cost": [
+		"20"
+	],
+	"filament_max_volumetric_speed": [
+		"12"
+	],
+	"nozzle_temperature": [
+		"215"
+	],
+	"nozzle_temperature_initial_layer": [
+		"220"
+	],
+	"nozzle_temperature_range_low": [
+		"190"
+	],
+	"nozzle_temperature_range_high": [
+		"240"
+	],
+	"temperature_vitrification": [
+		"45"
+	],
+	"hot_plate_temp": [
+		"75"
+	],
+	"hot_plate_temp_initial_layer": [
+		"75"
+	],
+	"cool_plate_temp": [
+		"75"
+	],
+	"cool_plate_temp_initial_layer": [
+		"75"
+	],
+	"textured_plate_temp": [
+		"75"
+	],
+	"textured_plate_temp_initial_layer": [
+		"75"
+	],
+	"fan_min_speed": [
+		"100"
+	],
+	"fan_max_speed": [
+		"100"
+	],
+	"overhang_fan_threshold": [
+		"50%"
+	],
+	"overhang_fan_speed": [
+		"100"
+	],
+	"close_fan_the_first_x_layers": [
+		"3"
+	],
+	"full_fan_speed_layer": [
+		"8"
+	],
+	"slow_down_min_speed": [
+		"20"
+	],
+	"slow_down_layer_time": [
+		"4"
+	],
+	"fan_cooling_layer_time": [
+		"100"
+	],
+	"reduce_fan_stop_start_freq": [
+		"1"
+	],
+	"filament_retraction_length": [
+		"1.5"
+	],
+	"filament_retraction_speed": [
+		"35"
+	],
+	"filament_deretraction_speed": [
+		"30"
+	],
+	"filament_start_gcode": [
+		"; Generic PLA @IdeaFormer IR3 V2 — belt PLA, bed 75C"
+	]
+}
@@ -0,0 +1,36 @@
+{
+	"type": "filament",
+	"name": "eSUN PLA @IdeaFormer IR3 V2",
+	"inherits": "Generic PLA @IdeaFormer IR3 V2",
+	"filament_id": "OFkrxQC4",
+	"from": "system",
+	"setting_id": "XqkviBmFHEglXueX",
+	"instantiation": "true",
+	"compatible_printers": [
+		"IdeaFormer IR3 V2 0.4 nozzle"
+	],
+	"filament_type": [
+		"PLA"
+	],
+	"filament_vendor": [
+		"eSUN"
+	],
+	"filament_settings_id": [
+		"eSUN PLA @IdeaFormer IR3 V2"
+	],
+	"nozzle_temperature_initial_layer": [
+		"200"
+	],
+	"nozzle_temperature": [
+		"200"
+	],
+	"enable_pressure_advance": [
+		"1"
+	],
+	"pressure_advance": [
+		"0.12"
+	],
+	"filament_max_volumetric_speed": [
+		"20"
+	]
+}
@@ -0,0 +1,91 @@
+{
+	"type": "machine",
+	"name": "IdeaFormer IR3 V2 0.4 nozzle",
+	"inherits": "fdm_belt_common",
+	"from": "system",
+	"setting_id": "MDQZgwRgg72lmjtu",
+	"instantiation": "true",
+	"printer_model": "IdeaFormer IR3 V2",
+	"printer_variant": "0.4",
+	"nozzle_diameter": [
+		"0.4"
+	],
+	"printable_area": [
+		"0x0",
+		"250x0",
+		"250x2000",
+		"0x2000"
+	],
+	"printable_height": "250",
+	"belt_printer_infinite_y": "1",
+	"thumbnails": [
+		"48x48/PNG",
+		"300x300/PNG"
+	],
+	"default_filament_profile": [
+		"Generic PLA @IdeaFormer IR3 V2"
+	],
+	"default_print_profile": "0.20mm Standard @IdeaFormer IR3 V2",
+	"use_relative_e_distances": "1",
+	"machine_max_acceleration_e": [
+		"5000"
+	],
+	"machine_max_acceleration_extruding": [
+		"5000"
+	],
+	"machine_max_acceleration_retracting": [
+		"1000"
+	],
+	"machine_max_acceleration_travel": [
+		"9000"
+	],
+	"machine_max_acceleration_x": [
+		"5000"
+	],
+	"machine_max_acceleration_y": [
+		"5000"
+	],
+	"machine_max_acceleration_z": [
+		"100"
+	],
+	"machine_max_jerk_e": [
+		"2.5"
+	],
+	"machine_max_jerk_x": [
+		"10"
+	],
+	"machine_max_jerk_y": [
+		"10"
+	],
+	"machine_max_jerk_z": [
+		"0.4"
+	],
+	"machine_max_speed_e": [
+		"60"
+	],
+	"machine_max_speed_x": [
+		"500"
+	],
+	"machine_max_speed_y": [
+		"500"
+	],
+	"machine_max_speed_z": [
+		"20"
+	],
+	"retraction_length": [
+		"2"
+	],
+	"retraction_speed": [
+		"40"
+	],
+	"deretraction_speed": [
+		"40"
+	],
+	"retract_lift_below": [
+		"300"
+	],
+	"machine_start_gcode": "; === IdeaFormer IR3 V2 Belt Printer Start ===\n; Axes: X=lateral, Y=gantry height (probe), Z=belt\nG90 ; absolute positioning\nM82 ; absolute extruder\nG21 ; millimeters\nG28 ; home all axes\nG1 Y20 F500 ; lift nozzle 20mm from belt\n; Bed + hotend temps come from the active filament profile. Belt PLA requires 75 C bed — use Generic/eSun PLA @IdeaFormer IR3 V2 filament presets to get it automatically.\nM140 S[hot_plate_temp_initial_layer] ; set bed temp\nM104 S[nozzle_temperature_initial_layer] ; hotend temp\nM109 S[nozzle_temperature_initial_layer] ; wait hotend\nM190 S[hot_plate_temp_initial_layer] ; wait bed\n; --- Purge blob ---\nG92 E0 ; zero extruder\nG1 Y.1 ; nozzle 0.1mm above belt\nG1 E15 F1000 ; purge 15mm blob\nG1 Z20 E25 F800 ; belt advance 20mm + extrude\nG1 E23 ; retract 2mm\nG28 Y ; re-probe belt surface\nG1 E25 ; de-retract\n; --- Prime lines (full 250mm bed width) ---\nFMS_on ; filament motion sensor\nG1 X250 E50 F2000 ; prime line 1\nG92 Z0 ; reset belt origin\nG1 Z.4 ; belt advance 0.4mm\nG1 X0 E75 ; prime line 2\nG1 F1000 ; default feedrate\nG92 E0 Z0 ; zero extruder + belt = print origin\n",
+	"machine_end_gcode": "; === IdeaFormer IR3 V2 Belt Printer End ===\nM400 ; wait for moves to finish\nM104 S0 ; heater off\nM140 S0 ; bed off\nG92 E0 ; zero extruder\nG1 E-5 F300 ; retract 5mm\nG4 P5000 ; wait for ooze\nG91 ; relative mode - keep every end move relative on a belt\nG1 Y20 F1000 ; raise gantry 20mm for clearance over the part\nG1 Z676 F3000 ; advance belt one full machine-depth to eject the part and clean the belt\nG90 ; back to absolute\nG28 X ; home X only - NEVER 'G28' all: that homes Z/belt and reverses the whole print back into the gantry\nFMS_off ; filament motion sensor off\nBED_MESH_CLEAR\nM84 ; disable motors\n",
+	"machine_pause_gcode": "PAUSE",
+	"layer_change_gcode": "G92 E0 ; belt: reset extruder at layer change (relative E)"
+}
@@ -0,0 +1,12 @@
+{
+	"type": "machine_model",
+	"name": "IdeaFormer IR3 V2",
+	"model_id": "IdeaFormer_IR3_V2",
+	"nozzle_diameter": "0.4",
+	"machine_tech": "FFF",
+	"family": "IdeaFormer",
+	"bed_model": "",
+	"bed_texture": "",
+	"hotend_model": "",
+	"default_materials": "Generic PLA @IdeaFormer IR3 V2;Generic PETG @IdeaFormer IR3 V2"
+}
@@ -0,0 +1,99 @@
+{
+	"type": "machine",
+	"name": "fdm_belt_common",
+	"inherits": "fdm_klipper_common",
+	"from": "system",
+	"instantiation": "false",
+	"gcode_flavor": "klipper",
+	"single_extruder_multi_material": "0",
+	"default_filament_profile": [
+		"Generic PLA @System"
+	],
+	"default_print_profile": "0.20mm Standard @IdeaFormer IR3 V2",
+	"max_layer_height": [
+		"0.32"
+	],
+	"min_layer_height": [
+		"0.08"
+	],
+	"deretraction_speed": [
+		"30"
+	],
+	"extruder_colour": [
+		"#FCE94F"
+	],
+	"extruder_offset": [
+		"0x0"
+	],
+	"long_retractions_when_cut": [
+		"0"
+	],
+	"nozzle_diameter": [
+		"0.4"
+	],
+	"retract_before_wipe": [
+		"70%"
+	],
+	"retract_length_toolchange": [
+		"2"
+	],
+	"retract_lift_above": [
+		"0"
+	],
+	"retract_lift_below": [
+		"0"
+	],
+	"retract_lift_enforce": [
+		"All Surfaces"
+	],
+	"retract_restart_extra": [
+		"0"
+	],
+	"retract_restart_extra_toolchange": [
+		"0"
+	],
+	"retract_when_changing_layer": [
+		"1"
+	],
+	"retraction_distances_when_cut": [
+		"18"
+	],
+	"retraction_length": [
+		"0.8"
+	],
+	"retraction_minimum_travel": [
+		"1"
+	],
+	"retraction_speed": [
+		"30"
+	],
+	"travel_slope": [
+		"3"
+	],
+	"wipe": [
+		"1"
+	],
+	"wipe_distance": [
+		"1"
+	],
+	"z_hop": [
+		"0"
+	],
+	"z_hop_types": [
+		"Normal Lift"
+	],
+	"gcode_remap_x": "rev_x",
+	"gcode_remap_y": "pos_z",
+	"gcode_remap_z": "pos_y",
+	"printer_extruder_id": [
+		"1"
+	],
+	"belt_printer": "1",
+	"belt_slice_rotation": "x",
+	"belt_slice_rotation_angle": "45",
+	"belt_slice_rotation_global": "1",
+	"build_plate_tilt_x": "45",
+	"purge_in_prime_tower": "0",
+	"scan_first_layer": "0",
+	"auxiliary_fan": "0"
+}
@@ -0,0 +1,141 @@
+{
+	"type": "machine",
+	"name": "fdm_klipper_common",
+	"inherits": "fdm_machine_common",
+	"from": "system",
+	"instantiation": "false",
+	"gcode_flavor": "klipper",
+	"machine_max_acceleration_e": [
+		"5000",
+		"5000"
+	],
+	"machine_max_acceleration_extruding": [
+		"20000",
+		"20000"
+	],
+	"machine_max_acceleration_retracting": [
+		"5000",
+		"5000"
+	],
+	"machine_max_acceleration_travel": [
+		"20000",
+		"20000"
+	],
+	"machine_max_acceleration_x": [
+		"20000",
+		"20000"
+	],
+	"machine_max_acceleration_y": [
+		"20000",
+		"20000"
+	],
+	"machine_max_acceleration_z": [
+		"500",
+		"200"
+	],
+	"machine_max_speed_e": [
+		"25",
+		"25"
+	],
+	"machine_max_speed_x": [
+		"500",
+		"200"
+	],
+	"machine_max_speed_y": [
+		"500",
+		"200"
+	],
+	"machine_max_speed_z": [
+		"12",
+		"12"
+	],
+	"machine_max_jerk_e": [
+		"2.5",
+		"2.5"
+	],
+	"machine_max_jerk_x": [
+		"9",
+		"9"
+	],
+	"machine_max_jerk_y": [
+		"9",
+		"9"
+	],
+	"machine_max_jerk_z": [
+		"0.2",
+		"0.4"
+	],
+	"machine_min_extruding_rate": [
+		"0",
+		"0"
+	],
+	"machine_min_travel_rate": [
+		"0",
+		"0"
+	],
+	"max_layer_height": [
+		"0.32"
+	],
+	"min_layer_height": [
+		"0.08"
+	],
+	"printable_height": "250",
+	"extruder_clearance_radius": "65",
+	"extruder_clearance_height_to_rod": "36",
+	"extruder_clearance_height_to_lid": "140",
+	"printer_settings_id": "",
+	"printer_technology": "FFF",
+	"printer_variant": "0.4",
+	"retraction_minimum_travel": [
+		"1"
+	],
+	"retract_before_wipe": [
+		"70%"
+	],
+	"retract_when_changing_layer": [
+		"1"
+	],
+	"retraction_length": [
+		"0.8"
+	],
+	"retract_length_toolchange": [
+		"2"
+	],
+	"z_hop": [
+		"0.4"
+	],
+	"retract_restart_extra": [
+		"0"
+	],
+	"retract_restart_extra_toolchange": [
+		"0"
+	],
+	"retraction_speed": [
+		"30"
+	],
+	"deretraction_speed": [
+		"30"
+	],
+	"z_hop_types": "Normal Lift",
+	"silent_mode": "0",
+	"single_extruder_multi_material": "1",
+	"change_filament_gcode": "",
+	"wipe": [
+		"1"
+	],
+	"default_filament_profile": [
+		"Generic PLA @System"
+	],
+	"default_print_profile": "0.20mm Standard @MyKlipper",
+	"bed_exclude_area": [
+		"0x0"
+	],
+	"machine_start_gcode": "M190 S[bed_temperature_initial_layer_single]\nM109 S[nozzle_temperature_initial_layer]\nPRINT_START EXTRUDER=[nozzle_temperature_initial_layer] BED=[bed_temperature_initial_layer_single]\n",
+	"machine_end_gcode": "PRINT_END",
+	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
+	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n",
+	"machine_pause_gcode": "PAUSE",
+	"scan_first_layer": "0",
+	"nozzle_type": "undefine",
+	"auxiliary_fan": "0"
+}
@@ -0,0 +1,119 @@
+{
+	"type": "machine",
+	"name": "fdm_machine_common",
+	"from": "system",
+	"instantiation": "false",
+	"printer_technology": "FFF",
+	"deretraction_speed": [
+		"40"
+	],
+	"extruder_colour": [
+		"#FCE94F"
+	],
+	"extruder_offset": [
+		"0x0"
+	],
+	"gcode_flavor": "marlin",
+	"silent_mode": "0",
+	"machine_max_acceleration_e": [
+		"5000"
+	],
+	"machine_max_acceleration_extruding": [
+		"10000"
+	],
+	"machine_max_acceleration_retracting": [
+		"1000"
+	],
+	"machine_max_acceleration_x": [
+		"10000"
+	],
+	"machine_max_acceleration_y": [
+		"10000"
+	],
+	"machine_max_acceleration_z": [
+		"500"
+	],
+	"machine_max_speed_e": [
+		"60"
+	],
+	"machine_max_speed_x": [
+		"500"
+	],
+	"machine_max_speed_y": [
+		"500"
+	],
+	"machine_max_speed_z": [
+		"10"
+	],
+	"machine_max_jerk_e": [
+		"5"
+	],
+	"machine_max_jerk_x": [
+		"8"
+	],
+	"machine_max_jerk_y": [
+		"8"
+	],
+	"machine_max_jerk_z": [
+		"0.4"
+	],
+	"machine_min_extruding_rate": [
+		"0"
+	],
+	"machine_min_travel_rate": [
+		"0"
+	],
+	"max_layer_height": [
+		"0.32"
+	],
+	"min_layer_height": [
+		"0.08"
+	],
+	"printable_height": "250",
+	"extruder_clearance_radius": "65",
+	"extruder_clearance_height_to_rod": "36",
+	"extruder_clearance_height_to_lid": "140",
+	"nozzle_diameter": [
+		"0.4"
+	],
+	"printer_settings_id": "",
+	"printer_variant": "0.4",
+	"retraction_minimum_travel": [
+		"2"
+	],
+	"retract_before_wipe": [
+		"70%"
+	],
+	"retract_when_changing_layer": [
+		"1"
+	],
+	"retraction_length": [
+		"1"
+	],
+	"retract_length_toolchange": [
+		"1"
+	],
+	"z_hop": [
+		"0"
+	],
+	"retract_restart_extra": [
+		"0"
+	],
+	"retract_restart_extra_toolchange": [
+		"0"
+	],
+	"retraction_speed": [
+		"60"
+	],
+	"single_extruder_multi_material": "1",
+	"change_filament_gcode": "",
+	"wipe": [
+		"1"
+	],
+	"default_print_profile": "",
+	"machine_start_gcode": "G0 Z20 F9000\nG92 E0; G1 E-10 F1200\nG28\nM970 Q1 A10 B10 C130 K0\nM970 Q1 A10 B131 C250 K1\nM974 Q1 S1 P0\nM970 Q0 A10 B10 C130 H20 K0\nM970 Q0 A10 B131 C250 K1\nM974 Q0 S1 P0\nM220 S100 ;Reset Feedrate\nM221 S100 ;Reset Flowrate\nG29 ;Home\nG90;\nG92 E0 ;Reset Extruder \nG1 Z2.0 F3000 ;Move Z Axis up \nG1 X10.1 Y20 Z0.28 F5000.0 ;Move to start position\nM109 S205;\nG1 X10.1 Y200.0 Z0.28 F1500.0 E15 ;Draw the first line\nG1 X10.4 Y200.0 Z0.28 F5000.0 ;Move to side a little\nG1 X10.4 Y20 Z0.28 F1500.0 E30 ;Draw the second line\nG92 E0 ;Reset Extruder \nG1 X110 Y110 Z2.0 F3000 ;Move Z Axis up",
+	"machine_end_gcode": "M400 ; wait for buffer to clear\nG92 E0 ; zero the extruder\nG1 E-4.0 F3600; retract \nG91\nG1 Z3;\nM104 S0 ; turn off hotend\nM140 S0 ; turn off bed\nM106 S0 ; turn off fan\nG90 \nG0 X110 Y200 F3600 \nprint_end",
+	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
+	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n",
+	"machine_pause_gcode": "M601"
+}
@@ -0,0 +1,23 @@
+{
+	"type": "process",
+	"name": "0.20mm Standard @IdeaFormer IR3 V2",
+	"inherits": "fdm_process_common",
+	"from": "system",
+	"setting_id": "91atcIwv5728phqX",
+	"instantiation": "true",
+	"layer_height": "0.2",
+	"initial_layer_print_height": "0.2",
+	"initial_layer_line_width": "0.42",
+	"wall_loops": "2",
+	"reduce_infill_retraction": "1",
+	"detect_overhang_wall": "1",
+	"skirt_loops": "0",
+	"skirt_distance": "0",
+	"sparse_infill_pattern": "grid",
+	"sparse_infill_speed": "200",
+	"support_base_pattern": "rectilinear",
+	"support_interface_pattern": "rectilinear",
+	"compatible_printers": [
+		"IdeaFormer IR3 V2 0.4 nozzle"
+	]
+}
@@ -0,0 +1,108 @@
+{
+	"type": "process",
+	"name": "fdm_process_common",
+	"from": "system",
+	"instantiation": "false",
+	"adaptive_layer_height": "0",
+	"reduce_crossing_wall": "0",
+	"max_travel_detour_distance": "0",
+	"bottom_surface_pattern": "monotonic",
+	"bottom_shell_thickness": "0",
+	"bridge_speed": "50",
+	"brim_width": "5",
+	"brim_object_gap": "0.1",
+	"compatible_printers": [],
+	"compatible_printers_condition": "",
+	"print_sequence": "by layer",
+	"default_acceleration": "1000",
+	"initial_layer_acceleration": "500",
+	"top_surface_acceleration": "1000",
+	"travel_acceleration": "1000",
+	"inner_wall_acceleration": "1000",
+	"outer_wall_acceleration": "700",
+	"bridge_no_support": "0",
+	"draft_shield": "disabled",
+	"elefant_foot_compensation": "0",
+	"enable_arc_fitting": "0",
+	"wall_infill_order": "inner wall/outer wall/infill",
+	"infill_direction": "45",
+	"sparse_infill_density": "15%",
+	"sparse_infill_pattern": "crosshatch",
+	"initial_layer_print_height": "0.2",
+	"infill_combination": "0",
+	"infill_wall_overlap": "25%",
+	"interface_shells": "0",
+	"ironing_flow": "10%",
+	"ironing_spacing": "0.15",
+	"ironing_speed": "30",
+	"ironing_type": "no ironing",
+	"reduce_infill_retraction": "1",
+	"filename_format": "{input_filename_base}_{layer_height}mm_{filament_type[initial_tool]}_{printer_model}_{print_time}.gcode",
+	"detect_overhang_wall": "1",
+	"slowdown_for_curled_perimeters": "1",
+	"overhang_1_4_speed": "0",
+	"overhang_2_4_speed": "50",
+	"overhang_3_4_speed": "30",
+	"overhang_4_4_speed": "10",
+	"line_width": "110%",
+	"inner_wall_line_width": "110%",
+	"outer_wall_line_width": "100%",
+	"top_surface_line_width": "93.75%",
+	"sparse_infill_line_width": "110%",
+	"initial_layer_line_width": "120%",
+	"internal_solid_infill_line_width": "120%",
+	"support_line_width": "96%",
+	"wall_loops": "3",
+	"print_settings_id": "",
+	"raft_layers": "0",
+	"seam_position": "aligned",
+	"skirt_distance": "2",
+	"skirt_height": "3",
+	"min_skirt_length": "4",
+	"skirt_loops": "0",
+	"minimum_sparse_infill_area": "15",
+	"spiral_mode": "0",
+	"standby_temperature_delta": "-5",
+	"enable_support": "0",
+	"resolution": "0.012",
+	"support_type": "normal(auto)",
+	"support_on_build_plate_only": "0",
+	"support_top_z_distance": "0.2",
+	"support_bottom_z_distance": "0.2",
+	"support_filament": "0",
+	"support_interface_loop_pattern": "0",
+	"support_interface_filament": "0",
+	"support_interface_top_layers": "2",
+	"support_interface_bottom_layers": "2",
+	"support_interface_spacing": "0.5",
+	"support_interface_speed": "80",
+	"support_base_pattern": "default",
+	"support_base_pattern_spacing": "2.5",
+	"support_speed": "150",
+	"support_threshold_angle": "30",
+	"support_object_xy_distance": "0.35",
+	"tree_support_branch_angle": "30",
+	"tree_support_wall_count": "0",
+	"tree_support_with_infill": "0",
+	"detect_thin_wall": "0",
+	"top_surface_pattern": "monotonicline",
+	"top_shell_thickness": "0.8",
+	"enable_prime_tower": "1",
+	"wipe_tower_no_sparse_layers": "0",
+	"prime_tower_width": "60",
+	"xy_hole_compensation": "0",
+	"xy_contour_compensation": "0",
+	"layer_height": "0.2",
+	"bottom_shell_layers": "3",
+	"top_shell_layers": "4",
+	"bridge_flow": "1",
+	"initial_layer_speed": "45",
+	"initial_layer_infill_speed": "45",
+	"outer_wall_speed": "45",
+	"inner_wall_speed": "80",
+	"sparse_infill_speed": "150",
+	"internal_solid_infill_speed": "150",
+	"top_surface_speed": "50",
+	"gap_infill_speed": "30",
+	"travel_speed": "200"
+}
@@ -0,0 +1,54 @@
+{
+	"name": "Printcepts",
+	"version": "01.00.00.03",
+	"force_update": "0",
+	"description": "Printcepts belt printer configurations",
+	"machine_model_list": [
+		{
+			"name": "BabyBelt Pro",
+			"sub_path": "machine/BabyBelt Pro.json"
+		}
+	],
+	"process_list": [
+		{
+			"name": "fdm_process_common",
+			"sub_path": "process/fdm_process_common.json"
+		},
+		{
+			"name": "0.20mm Standard @BabyBelt Pro",
+			"sub_path": "process/0.20mm Standard @BabyBelt Pro.json"
+		}
+	],
+	"filament_list": [
+		{
+			"name": "Generic PLA @BabyBelt Pro",
+			"sub_path": "filament/Generic PLA @BabyBelt Pro.json"
+		},
+		{
+			"name": "eSUN PLA @BabyBelt Pro",
+			"sub_path": "filament/eSUN PLA @BabyBelt Pro.json"
+		},
+		{
+			"name": "Generic PETG @BabyBelt Pro",
+			"sub_path": "filament/Generic PETG @BabyBelt Pro.json"
+		}
+	],
+	"machine_list": [
+		{
+			"name": "fdm_machine_common",
+			"sub_path": "machine/fdm_machine_common.json"
+		},
+		{
+			"name": "fdm_klipper_common",
+			"sub_path": "machine/fdm_klipper_common.json"
+		},
+		{
+			"name": "fdm_belt_common",
+			"sub_path": "machine/fdm_belt_common.json"
+		},
+		{
+			"name": "BabyBelt Pro 0.4 nozzle",
+			"sub_path": "machine/BabyBelt Pro 0.4 nozzle.json"
+		}
+	]
+}
@@ -0,0 +1,70 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="95.0mm" height="500.0mm" viewBox="0 0 95.0 500.0" preserveAspectRatio="xMidYMid meet">
+  <!-- Printcepts BabyBelt Pro bed texture: 95 x 500 mm belt plate. -->
+  <!-- Transparent plate; green (#195F30) BabyBelt Pro logo centered along X, near the bottom edge. -->
+  <rect x="0" y="0" width="95.0" height="500.0" fill="none"/>
+  <g transform="translate(14.2500,436.3488) scale(0.067538)">
+    <g transform="translate(-11.000000,692.938562) scale(0.100000,-0.100000)"
+fill="#195F30" stroke="none">
+<path d="M1963 5604 l-1423 -1324 0 -2050 0 -2050 443 0 c244 0 741 3 1105 7
+l662 6 0 746 c-1 575 -4 768 -14 841 -47 324 -179 486 -473 581 -40 12 -73 26
+-73 30 0 4 32 17 72 29 212 64 333 166 378 320 35 121 38 191 32 868 l-5 662
+-629 0 c-395 0 -628 4 -628 10 0 5 635 601 1410 1325 776 724 1410 1318 1410
+1321 0 2 -190 4 -422 3 l-423 0 -1422 -1325z m-334 -2029 c143 -16 174 -96
+173 -446 -2 -411 -24 -458 -224 -462 l-93 -2 -3 450 c-1 248 0 456 3 463 3 9
+18 12 47 8 24 -3 67 -8 97 -11z m-4 -1556 c160 -29 173 -62 182 -469 9 -455
+-14 -593 -108 -641 -39 -19 -193 -44 -210 -33 -10 6 -13 1147 -3 1157 6 6 45
+2 139 -14z"/>
+<path d="M3464 5979 c-142 -132 -263 -245 -268 -250 -6 -5 69 -9 190 -9 l199
+1 268 249 267 250 -198 0 -198 0 -260 -241z"/>
+<path d="M3650 5649 c-135 -126 -254 -238 -265 -249 -19 -20 -18 -20 177 -20
+l197 0 228 211 c125 116 246 229 268 250 l40 39 -200 -1 -200 0 -245 -230z"/>
+<path d="M2537 5089 c-101 -24 -204 -105 -251 -197 -96 -190 -19 -420 172
+-514 l67 -33 2670 0 2670 0 57 27 c74 34 146 107 184 183 43 88 43 230 0 322
+-35 76 -113 153 -193 191 l-58 27 -2640 2 c-1513 0 -2656 -3 -2678 -8z m5063
+-77 c-57 -37 -118 -111 -140 -168 -31 -82 -25 -206 12 -279 26 -49 93 -121
+133 -143 15 -8 -640 -11 -2410 -11 l-2430 0 30 21 c200 146 201 425 1 569
+l-39 29 2434 -1 c2263 0 2432 -1 2409 -17z m-4890 -43 c270 -122 185 -526
+-109 -522 -257 2 -370 324 -170 485 74 60 194 76 279 37z m5201 -12 c94 -55
+140 -135 140 -242 0 -285 -393 -374 -517 -117 -26 54 -30 162 -9 219 28 74 97
+139 173 164 53 17 166 4 213 -24z"/>
+<path d="M2917 3973 c-4 -174 -7 -550 -7 -835 l0 -518 326 0 326 0 -7 150 -7
+150 110 0 110 0 11 -32 c5 -18 26 -86 46 -150 l36 -118 325 0 c179 0 323 4
+320 9 -3 4 -155 374 -337 822 -182 448 -333 820 -336 827 -4 9 -105 12 -457
+12 l-453 0 -6 -317z m773 -745 c0 -5 -47 -8 -104 -8 l-103 0 -7 92 c-3 50 -6
+202 -5 337 l1 246 109 -330 c60 -181 109 -333 109 -337z"/>
+<path d="M4680 3455 l0 -835 448 0 c693 1 885 16 985 80 99 63 126 132 134
+340 12 327 -44 405 -342 476 -28 7 -27 8 25 19 199 42 255 95 267 248 11 146
+-32 285 -110 353 -145 126 -329 153 -1049 154 l-358 0 0 -835z m846 520 c36
+-23 44 -54 44 -162 0 -152 -29 -183 -170 -183 l-40 0 0 186 0 187 71 -6 c39
+-3 82 -13 95 -22z m4 -625 c33 -18 40 -52 40 -208 0 -200 -9 -214 -143 -228
+l-67 -7 0 233 0 233 74 -6 c41 -3 84 -10 96 -17z"/>
+<path d="M6150 4286 c0 -3 131 -242 290 -531 l290 -526 0 -304 0 -305 385 0
+385 0 0 299 0 299 305 533 305 534 -377 3 c-207 1 -381 -2 -385 -6 -16 -16
+-110 -258 -172 -444 l-62 -187 -18 77 c-18 75 -139 450 -171 525 l-15 37 -380
+0 c-209 0 -380 -2 -380 -4z"/>
+<path d="M2910 1355 l0 -1185 830 0 830 0 0 240 0 240 -350 0 -350 0 0 255 0
+255 300 0 300 0 0 230 0 230 -300 0 -300 0 0 220 0 220 320 0 320 0 0 240 0
+240 -800 0 -800 0 0 -1185z"/>
+<path d="M4680 1355 l0 -1185 775 0 775 0 0 240 0 240 -295 0 -295 0 0 945 0
+945 -480 0 -480 0 0 -1185z"/>
+<path d="M5800 2300 l0 -240 280 0 280 0 0 -945 0 -945 480 0 480 0 0 945 0
+945 285 0 285 0 0 240 0 240 -1045 0 -1045 0 0 -240z"/>
+<path d="M8032 1358 l-2 -1188 1008 1 c621 1 971 5 912 10 -309 27 -631 139
+-885 306 -593 391 -984 1122 -1025 1918 -4 77 -8 -394 -8 -1047z"/>
+<path d="M7441 1934 c-43 -36 -59 -70 -70 -148 -18 -124 16 -252 76 -291 32
+-21 226 -33 328 -20 114 14 161 97 153 269 -5 96 -24 151 -68 191 -20 18 -39
+20 -205 23 l-182 3 -32 -27z m389 -199 c7 -8 10 -22 6 -30 -4 -13 -34 -15
+-186 -15 -189 0 -202 3 -186 45 8 22 348 22 366 0z"/>
+<path d="M7450 1267 c-14 -6 -35 -32 -47 -57 -21 -41 -23 -58 -23 -222 l0
+-178 270 0 270 0 0 105 0 105 -121 0 -120 0 3 28 3 27 118 3 117 3 0 99 0 100
+-113 0 c-121 0 -138 -7 -162 -65 -8 -19 -9 -19 -12 2 -10 55 -116 84 -183 50z
+m134 -203 c15 -38 8 -44 -54 -44 -62 0 -69 6 -54 44 9 23 99 23 108 0z"/>
+<path d="M466 1193 l-29 -43 -163 0 -164 0 0 -235 0 -235 165 0 165 0 27 -42
+28 -42 3 163 c1 89 1 233 0 319 l-3 157 -29 -42z"/>
+<path d="M7443 620 c-48 -20 -58 -60 -61 -262 l-4 -188 271 0 271 0 0 110 0
+110 -110 0 -110 0 0 70 c0 76 -21 145 -51 160 -22 12 -176 12 -206 0z m161
+-186 c15 -39 8 -44 -64 -44 -72 0 -79 5 -64 44 9 23 119 23 128 0z"/>
+</g>
+  </g>
+</svg>
@@ -0,0 +1,110 @@
+{
+	"type": "filament",
+	"name": "Generic PETG @BabyBelt Pro",
+	"inherits": "Generic PETG @System",
+	"from": "system",
+	"setting_id": "gCzHpDNgVwQR6tgk",
+	"instantiation": "true",
+	"compatible_printers": [
+		"BabyBelt Pro 0.4 nozzle"
+	],
+	"filament_type": [
+		"PETG"
+	],
+	"filament_vendor": [
+		"Generic"
+	],
+	"filament_settings_id": [
+		"Generic PETG @BabyBelt Pro"
+	],
+	"filament_diameter": [
+		"1.75"
+	],
+	"filament_density": [
+		"1.27"
+	],
+	"filament_flow_ratio": [
+		"0.95"
+	],
+	"filament_cost": [
+		"25"
+	],
+	"filament_max_volumetric_speed": [
+		"10"
+	],
+	"nozzle_temperature": [
+		"240"
+	],
+	"nozzle_temperature_initial_layer": [
+		"245"
+	],
+	"nozzle_temperature_range_low": [
+		"220"
+	],
+	"nozzle_temperature_range_high": [
+		"260"
+	],
+	"temperature_vitrification": [
+		"70"
+	],
+	"hot_plate_temp": [
+		"80"
+	],
+	"hot_plate_temp_initial_layer": [
+		"80"
+	],
+	"cool_plate_temp": [
+		"80"
+	],
+	"cool_plate_temp_initial_layer": [
+		"80"
+	],
+	"textured_plate_temp": [
+		"80"
+	],
+	"textured_plate_temp_initial_layer": [
+		"80"
+	],
+	"fan_min_speed": [
+		"40"
+	],
+	"fan_max_speed": [
+		"60"
+	],
+	"overhang_fan_threshold": [
+		"25%"
+	],
+	"overhang_fan_speed": [
+		"80"
+	],
+	"close_fan_the_first_x_layers": [
+		"3"
+	],
+	"full_fan_speed_layer": [
+		"8"
+	],
+	"slow_down_min_speed": [
+		"20"
+	],
+	"slow_down_layer_time": [
+		"4"
+	],
+	"fan_cooling_layer_time": [
+		"100"
+	],
+	"reduce_fan_stop_start_freq": [
+		"1"
+	],
+	"filament_retraction_length": [
+		"2"
+	],
+	"filament_retraction_speed": [
+		"40"
+	],
+	"filament_deretraction_speed": [
+		"40"
+	],
+	"filament_start_gcode": [
+		"; Generic PETG @BabyBelt Pro — belt PETG, bed 80C"
+	]
+}
@@ -0,0 +1,110 @@
+{
+	"type": "filament",
+	"name": "Generic PLA @BabyBelt Pro",
+	"inherits": "Generic PLA @System",
+	"from": "system",
+	"setting_id": "24PpcnhVx9v5f4fD",
+	"instantiation": "true",
+	"compatible_printers": [
+		"BabyBelt Pro 0.4 nozzle"
+	],
+	"filament_type": [
+		"PLA"
+	],
+	"filament_vendor": [
+		"Generic"
+	],
+	"filament_settings_id": [
+		"Generic PLA @BabyBelt Pro"
+	],
+	"filament_diameter": [
+		"1.75"
+	],
+	"filament_density": [
+		"1.24"
+	],
+	"filament_flow_ratio": [
+		"0.98"
+	],
+	"filament_cost": [
+		"20"
+	],
+	"filament_max_volumetric_speed": [
+		"12"
+	],
+	"nozzle_temperature": [
+		"215"
+	],
+	"nozzle_temperature_initial_layer": [
+		"220"
+	],
+	"nozzle_temperature_range_low": [
+		"190"
+	],
+	"nozzle_temperature_range_high": [
+		"240"
+	],
+	"temperature_vitrification": [
+		"45"
+	],
+	"hot_plate_temp": [
+		"75"
+	],
+	"hot_plate_temp_initial_layer": [
+		"75"
+	],
+	"cool_plate_temp": [
+		"75"
+	],
+	"cool_plate_temp_initial_layer": [
+		"75"
+	],
+	"textured_plate_temp": [
+		"75"
+	],
+	"textured_plate_temp_initial_layer": [
+		"75"
+	],
+	"fan_min_speed": [
+		"100"
+	],
+	"fan_max_speed": [
+		"100"
+	],
+	"overhang_fan_threshold": [
+		"50%"
+	],
+	"overhang_fan_speed": [
+		"100"
+	],
+	"close_fan_the_first_x_layers": [
+		"3"
+	],
+	"full_fan_speed_layer": [
+		"8"
+	],
+	"slow_down_min_speed": [
+		"20"
+	],
+	"slow_down_layer_time": [
+		"4"
+	],
+	"fan_cooling_layer_time": [
+		"100"
+	],
+	"reduce_fan_stop_start_freq": [
+		"1"
+	],
+	"filament_retraction_length": [
+		"1.5"
+	],
+	"filament_retraction_speed": [
+		"35"
+	],
+	"filament_deretraction_speed": [
+		"30"
+	],
+	"filament_start_gcode": [
+		"; Generic PLA @BabyBelt Pro — belt PLA, bed 75C"
+	]
+}
@@ -0,0 +1,36 @@
+{
+	"type": "filament",
+	"name": "eSUN PLA @BabyBelt Pro",
+	"inherits": "Generic PLA @BabyBelt Pro",
+	"filament_id": "OFkrxQC4",
+	"from": "system",
+	"setting_id": "EH3X7oE0DU5tSpjW",
+	"instantiation": "true",
+	"compatible_printers": [
+		"BabyBelt Pro 0.4 nozzle"
+	],
+	"filament_type": [
+		"PLA"
+	],
+	"filament_vendor": [
+		"eSUN"
+	],
+	"filament_settings_id": [
+		"eSUN PLA @BabyBelt Pro"
+	],
+	"nozzle_temperature_initial_layer": [
+		"200"
+	],
+	"nozzle_temperature": [
+		"200"
+	],
+	"enable_pressure_advance": [
+		"1"
+	],
+	"pressure_advance": [
+		"0.12"
+	],
+	"filament_max_volumetric_speed": [
+		"20"
+	]
+}
@@ -0,0 +1,87 @@
+{
+	"type": "machine",
+	"name": "BabyBelt Pro 0.4 nozzle",
+	"inherits": "fdm_belt_common",
+	"from": "system",
+	"setting_id": "34OWINlJpJgA9DwQ",
+	"instantiation": "true",
+	"printer_model": "BabyBelt Pro",
+	"printer_variant": "0.4",
+	"nozzle_diameter": [
+		"0.4"
+	],
+	"default_filament_profile": [
+		"Generic PLA @BabyBelt Pro"
+	],
+	"default_print_profile": "0.20mm Standard @BabyBelt Pro",
+	"printable_area": [
+		"0x0",
+		"95x0",
+		"95x500",
+		"0x500"
+	],
+	"printable_height": "100",
+	"best_object_pos": "0.5,0.05",
+	"nozzle_type": [
+		"hardened_steel"
+	],
+	"printer_extruder_id": [
+		"1"
+	],
+	"printer_extruder_variant": [
+		"Direct Drive Standard"
+	],
+	"thumbnails": [
+		"48x48/PNG",
+		"300x300/PNG"
+	],
+	"machine_max_acceleration_e": [
+		"500",
+		"5000"
+	],
+	"machine_max_acceleration_extruding": [
+		"500",
+		"20000"
+	],
+	"machine_max_acceleration_retracting": [
+		"500",
+		"5000"
+	],
+	"machine_max_acceleration_x": [
+		"500",
+		"20000"
+	],
+	"machine_max_acceleration_y": [
+		"500",
+		"20000"
+	],
+	"machine_max_junction_deviation": [
+		"0.01"
+	],
+	"machine_max_speed_x": [
+		"50",
+		"200"
+	],
+	"machine_max_speed_y": [
+		"50",
+		"200"
+	],
+	"machine_max_speed_z": [
+		"5",
+		"12"
+	],
+	"retraction_length": [
+		"1.5"
+	],
+	"retraction_speed": [
+		"20"
+	],
+	"deretraction_speed": [
+		"25"
+	],
+	"retract_lift_enforce": [
+		"Top and Bottom"
+	],
+	"support_chamber_temp_control": "0",
+	"machine_start_gcode": ";Start GCode\nPRINT_START ANGLE=[belt_slice_rotation_angle] EXTRUDER=[nozzle_temperature_initial_layer] BED=[hot_plate_temp_initial_layer] MATERIAL=[filament_type]\n"
+}
@@ -0,0 +1,12 @@
+{
+	"type": "machine_model",
+	"name": "BabyBelt Pro",
+	"model_id": "Printcepts_BabyBelt_Pro",
+	"nozzle_diameter": "0.4",
+	"machine_tech": "FFF",
+	"family": "Printcepts",
+	"bed_model": "",
+	"bed_texture": "BabyBelt Pro_bed_texture.svg",
+	"hotend_model": "",
+	"default_materials": "Generic PLA @BabyBelt Pro;Generic PETG @BabyBelt Pro"
+}
@@ -0,0 +1,99 @@
+{
+	"type": "machine",
+	"name": "fdm_belt_common",
+	"inherits": "fdm_klipper_common",
+	"from": "system",
+	"instantiation": "false",
+	"gcode_flavor": "klipper",
+	"single_extruder_multi_material": "0",
+	"default_filament_profile": [
+		"Generic PLA @System"
+	],
+	"default_print_profile": "0.20mm Standard @BabyBelt Pro",
+	"max_layer_height": [
+		"0.32"
+	],
+	"min_layer_height": [
+		"0.08"
+	],
+	"deretraction_speed": [
+		"30"
+	],
+	"extruder_colour": [
+		"#FCE94F"
+	],
+	"extruder_offset": [
+		"0x0"
+	],
+	"long_retractions_when_cut": [
+		"0"
+	],
+	"nozzle_diameter": [
+		"0.4"
+	],
+	"retract_before_wipe": [
+		"70%"
+	],
+	"retract_length_toolchange": [
+		"2"
+	],
+	"retract_lift_above": [
+		"0"
+	],
+	"retract_lift_below": [
+		"0"
+	],
+	"retract_lift_enforce": [
+		"All Surfaces"
+	],
+	"retract_restart_extra": [
+		"0"
+	],
+	"retract_restart_extra_toolchange": [
+		"0"
+	],
+	"retract_when_changing_layer": [
+		"1"
+	],
+	"retraction_distances_when_cut": [
+		"18"
+	],
+	"retraction_length": [
+		"0.8"
+	],
+	"retraction_minimum_travel": [
+		"1"
+	],
+	"retraction_speed": [
+		"30"
+	],
+	"travel_slope": [
+		"3"
+	],
+	"wipe": [
+		"1"
+	],
+	"wipe_distance": [
+		"1"
+	],
+	"z_hop": [
+		"0"
+	],
+	"z_hop_types": [
+		"Normal Lift"
+	],
+	"gcode_remap_x": "rev_x",
+	"gcode_remap_y": "pos_z",
+	"gcode_remap_z": "pos_y",
+	"printer_extruder_id": [
+		"1"
+	],
+	"belt_printer": "1",
+	"belt_slice_rotation": "x",
+	"belt_slice_rotation_angle": "45",
+	"belt_slice_rotation_global": "1",
+	"build_plate_tilt_x": "45",
+	"purge_in_prime_tower": "0",
+	"scan_first_layer": "0",
+	"auxiliary_fan": "0"
+}
@@ -0,0 +1,141 @@
+{
+	"type": "machine",
+	"name": "fdm_klipper_common",
+	"inherits": "fdm_machine_common",
+	"from": "system",
+	"instantiation": "false",
+	"gcode_flavor": "klipper",
+	"machine_max_acceleration_e": [
+		"5000",
+		"5000"
+	],
+	"machine_max_acceleration_extruding": [
+		"20000",
+		"20000"
+	],
+	"machine_max_acceleration_retracting": [
+		"5000",
+		"5000"
+	],
+	"machine_max_acceleration_travel": [
+		"20000",
+		"20000"
+	],
+	"machine_max_acceleration_x": [
+		"20000",
+		"20000"
+	],
+	"machine_max_acceleration_y": [
+		"20000",
+		"20000"
+	],
+	"machine_max_acceleration_z": [
+		"500",
+		"200"
+	],
+	"machine_max_speed_e": [
+		"25",
+		"25"
+	],
+	"machine_max_speed_x": [
+		"500",
+		"200"
+	],
+	"machine_max_speed_y": [
+		"500",
+		"200"
+	],
+	"machine_max_speed_z": [
+		"12",
+		"12"
+	],
+	"machine_max_jerk_e": [
+		"2.5",
+		"2.5"
+	],
+	"machine_max_jerk_x": [
+		"9",
+		"9"
+	],
+	"machine_max_jerk_y": [
+		"9",
+		"9"
+	],
+	"machine_max_jerk_z": [
+		"0.2",
+		"0.4"
+	],
+	"machine_min_extruding_rate": [
+		"0",
+		"0"
+	],
+	"machine_min_travel_rate": [
+		"0",
+		"0"
+	],
+	"max_layer_height": [
+		"0.32"
+	],
+	"min_layer_height": [
+		"0.08"
+	],
+	"printable_height": "250",
+	"extruder_clearance_radius": "65",
+	"extruder_clearance_height_to_rod": "36",
+	"extruder_clearance_height_to_lid": "140",
+	"printer_settings_id": "",
+	"printer_technology": "FFF",
+	"printer_variant": "0.4",
+	"retraction_minimum_travel": [
+		"1"
+	],
+	"retract_before_wipe": [
+		"70%"
+	],
+	"retract_when_changing_layer": [
+		"1"
+	],
+	"retraction_length": [
+		"0.8"
+	],
+	"retract_length_toolchange": [
+		"2"
+	],
+	"z_hop": [
+		"0.4"
+	],
+	"retract_restart_extra": [
+		"0"
+	],
+	"retract_restart_extra_toolchange": [
+		"0"
+	],
+	"retraction_speed": [
+		"30"
+	],
+	"deretraction_speed": [
+		"30"
+	],
+	"z_hop_types": "Normal Lift",
+	"silent_mode": "0",
+	"single_extruder_multi_material": "1",
+	"change_filament_gcode": "",
+	"wipe": [
+		"1"
+	],
+	"default_filament_profile": [
+		"Generic PLA @System"
+	],
+	"default_print_profile": "0.20mm Standard @MyKlipper",
+	"bed_exclude_area": [
+		"0x0"
+	],
+	"machine_start_gcode": "M190 S[bed_temperature_initial_layer_single]\nM109 S[nozzle_temperature_initial_layer]\nPRINT_START EXTRUDER=[nozzle_temperature_initial_layer] BED=[bed_temperature_initial_layer_single]\n",
+	"machine_end_gcode": "PRINT_END",
+	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
+	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n",
+	"machine_pause_gcode": "PAUSE",
+	"scan_first_layer": "0",
+	"nozzle_type": "undefine",
+	"auxiliary_fan": "0"
+}
@@ -0,0 +1,119 @@
+{
+	"type": "machine",
+	"name": "fdm_machine_common",
+	"from": "system",
+	"instantiation": "false",
+	"printer_technology": "FFF",
+	"deretraction_speed": [
+		"40"
+	],
+	"extruder_colour": [
+		"#FCE94F"
+	],
+	"extruder_offset": [
+		"0x0"
+	],
+	"gcode_flavor": "marlin",
+	"silent_mode": "0",
+	"machine_max_acceleration_e": [
+		"5000"
+	],
+	"machine_max_acceleration_extruding": [
+		"10000"
+	],
+	"machine_max_acceleration_retracting": [
+		"1000"
+	],
+	"machine_max_acceleration_x": [
+		"10000"
+	],
+	"machine_max_acceleration_y": [
+		"10000"
+	],
+	"machine_max_acceleration_z": [
+		"500"
+	],
+	"machine_max_speed_e": [
+		"60"
+	],
+	"machine_max_speed_x": [
+		"500"
+	],
+	"machine_max_speed_y": [
+		"500"
+	],
+	"machine_max_speed_z": [
+		"10"
+	],
+	"machine_max_jerk_e": [
+		"5"
+	],
+	"machine_max_jerk_x": [
+		"8"
+	],
+	"machine_max_jerk_y": [
+		"8"
+	],
+	"machine_max_jerk_z": [
+		"0.4"
+	],
+	"machine_min_extruding_rate": [
+		"0"
+	],
+	"machine_min_travel_rate": [
+		"0"
+	],
+	"max_layer_height": [
+		"0.32"
+	],
+	"min_layer_height": [
+		"0.08"
+	],
+	"printable_height": "250",
+	"extruder_clearance_radius": "65",
+	"extruder_clearance_height_to_rod": "36",
+	"extruder_clearance_height_to_lid": "140",
+	"nozzle_diameter": [
+		"0.4"
+	],
+	"printer_settings_id": "",
+	"printer_variant": "0.4",
+	"retraction_minimum_travel": [
+		"2"
+	],
+	"retract_before_wipe": [
+		"70%"
+	],
+	"retract_when_changing_layer": [
+		"1"
+	],
+	"retraction_length": [
+		"1"
+	],
+	"retract_length_toolchange": [
+		"1"
+	],
+	"z_hop": [
+		"0"
+	],
+	"retract_restart_extra": [
+		"0"
+	],
+	"retract_restart_extra_toolchange": [
+		"0"
+	],
+	"retraction_speed": [
+		"60"
+	],
+	"single_extruder_multi_material": "1",
+	"change_filament_gcode": "",
+	"wipe": [
+		"1"
+	],
+	"default_print_profile": "",
+	"machine_start_gcode": "G0 Z20 F9000\nG92 E0; G1 E-10 F1200\nG28\nM970 Q1 A10 B10 C130 K0\nM970 Q1 A10 B131 C250 K1\nM974 Q1 S1 P0\nM970 Q0 A10 B10 C130 H20 K0\nM970 Q0 A10 B131 C250 K1\nM974 Q0 S1 P0\nM220 S100 ;Reset Feedrate\nM221 S100 ;Reset Flowrate\nG29 ;Home\nG90;\nG92 E0 ;Reset Extruder \nG1 Z2.0 F3000 ;Move Z Axis up \nG1 X10.1 Y20 Z0.28 F5000.0 ;Move to start position\nM109 S205;\nG1 X10.1 Y200.0 Z0.28 F1500.0 E15 ;Draw the first line\nG1 X10.4 Y200.0 Z0.28 F5000.0 ;Move to side a little\nG1 X10.4 Y20 Z0.28 F1500.0 E30 ;Draw the second line\nG92 E0 ;Reset Extruder \nG1 X110 Y110 Z2.0 F3000 ;Move Z Axis up",
+	"machine_end_gcode": "M400 ; wait for buffer to clear\nG92 E0 ; zero the extruder\nG1 E-4.0 F3600; retract \nG91\nG1 Z3;\nM104 S0 ; turn off hotend\nM140 S0 ; turn off bed\nM106 S0 ; turn off fan\nG90 \nG0 X110 Y200 F3600 \nprint_end",
+	"layer_change_gcode": ";AFTER_LAYER_CHANGE\n;[layer_z]",
+	"before_layer_change_gcode": ";BEFORE_LAYER_CHANGE\n;[layer_z]\nG92 E0\n",
+	"machine_pause_gcode": "M601"
+}
@@ -0,0 +1,23 @@
+{
+	"type": "process",
+	"name": "0.20mm Standard @BabyBelt Pro",
+	"inherits": "fdm_process_common",
+	"from": "system",
+	"setting_id": "JGfGtqX6CWjCt437",
+	"instantiation": "true",
+	"layer_height": "0.2",
+	"initial_layer_print_height": "0.2",
+	"initial_layer_line_width": "0.42",
+	"wall_loops": "2",
+	"reduce_infill_retraction": "1",
+	"detect_overhang_wall": "1",
+	"skirt_loops": "0",
+	"skirt_distance": "0",
+	"sparse_infill_pattern": "grid",
+	"sparse_infill_speed": "200",
+	"support_base_pattern": "rectilinear",
+	"support_interface_pattern": "rectilinear",
+	"compatible_printers": [
+		"BabyBelt Pro 0.4 nozzle"
+	]
+}
@@ -0,0 +1,108 @@
+{
+	"type": "process",
+	"name": "fdm_process_common",
+	"from": "system",
+	"instantiation": "false",
+	"adaptive_layer_height": "0",
+	"reduce_crossing_wall": "0",
+	"max_travel_detour_distance": "0",
+	"bottom_surface_pattern": "monotonic",
+	"bottom_shell_thickness": "0",
+	"bridge_speed": "50",
+	"brim_width": "5",
+	"brim_object_gap": "0.1",
+	"compatible_printers": [],
+	"compatible_printers_condition": "",
+	"print_sequence": "by layer",
+	"default_acceleration": "1000",
+	"initial_layer_acceleration": "500",
+	"top_surface_acceleration": "1000",
+	"travel_acceleration": "1000",
+	"inner_wall_acceleration": "1000",
+	"outer_wall_acceleration": "700",
+	"bridge_no_support": "0",
+	"draft_shield": "disabled",
+	"elefant_foot_compensation": "0",
+	"enable_arc_fitting": "0",
+	"wall_infill_order": "inner wall/outer wall/infill",
+	"infill_direction": "45",
+	"sparse_infill_density": "15%",
+	"sparse_infill_pattern": "crosshatch",
+	"initial_layer_print_height": "0.2",
+	"infill_combination": "0",
+	"infill_wall_overlap": "25%",
+	"interface_shells": "0",
+	"ironing_flow": "10%",
+	"ironing_spacing": "0.15",
+	"ironing_speed": "30",
+	"ironing_type": "no ironing",
+	"reduce_infill_retraction": "1",
+	"filename_format": "{input_filename_base}_{layer_height}mm_{filament_type[initial_tool]}_{printer_model}_{print_time}.gcode",
+	"detect_overhang_wall": "1",
+	"slowdown_for_curled_perimeters": "1",
+	"overhang_1_4_speed": "0",
+	"overhang_2_4_speed": "50",
+	"overhang_3_4_speed": "30",
+	"overhang_4_4_speed": "10",
+	"line_width": "110%",
+	"inner_wall_line_width": "110%",
+	"outer_wall_line_width": "100%",
+	"top_surface_line_width": "93.75%",
+	"sparse_infill_line_width": "110%",
+	"initial_layer_line_width": "120%",
+	"internal_solid_infill_line_width": "120%",
+	"support_line_width": "96%",
+	"wall_loops": "3",
+	"print_settings_id": "",
+	"raft_layers": "0",
+	"seam_position": "aligned",
+	"skirt_distance": "2",
+	"skirt_height": "3",
+	"min_skirt_length": "4",
+	"skirt_loops": "0",
+	"minimum_sparse_infill_area": "15",
+	"spiral_mode": "0",
+	"standby_temperature_delta": "-5",
+	"enable_support": "0",
+	"resolution": "0.012",
+	"support_type": "normal(auto)",
+	"support_on_build_plate_only": "0",
+	"support_top_z_distance": "0.2",
+	"support_bottom_z_distance": "0.2",
+	"support_filament": "0",
+	"support_interface_loop_pattern": "0",
+	"support_interface_filament": "0",
+	"support_interface_top_layers": "2",
+	"support_interface_bottom_layers": "2",
+	"support_interface_spacing": "0.5",
+	"support_interface_speed": "80",
+	"support_base_pattern": "default",
+	"support_base_pattern_spacing": "2.5",
+	"support_speed": "150",
+	"support_threshold_angle": "30",
+	"support_object_xy_distance": "0.35",
+	"tree_support_branch_angle": "30",
+	"tree_support_wall_count": "0",
+	"tree_support_with_infill": "0",
+	"detect_thin_wall": "0",
+	"top_surface_pattern": "monotonicline",
+	"top_shell_thickness": "0.8",
+	"enable_prime_tower": "1",
+	"wipe_tower_no_sparse_layers": "0",
+	"prime_tower_width": "60",
+	"xy_hole_compensation": "0",
+	"xy_contour_compensation": "0",
+	"layer_height": "0.2",
+	"bottom_shell_layers": "3",
+	"top_shell_layers": "4",
+	"bridge_flow": "1",
+	"initial_layer_speed": "45",
+	"initial_layer_infill_speed": "45",
+	"outer_wall_speed": "45",
+	"inner_wall_speed": "80",
+	"sparse_infill_speed": "150",
+	"internal_solid_infill_speed": "150",
+	"top_surface_speed": "50",
+	"gap_infill_speed": "30",
+	"travel_speed": "200"
+}
@@ -26,6 +26,7 @@ struct SlopeDetection
    bool actived;
 	float normal_z;
    mat3 volume_world_normal_matrix;
+    vec3 up_direction;
 };

 uniform vec4 uniform_color;
@@ -23,6 +23,7 @@ struct SlopeDetection
    bool actived;
 	float normal_z;
    mat3 volume_world_normal_matrix;
+    vec3 up_direction;
 };

 uniform mat4 view_model_matrix;
@@ -73,8 +74,8 @@ void main()
    // Point in homogenous coordinates.
    world_pos = volume_world_matrix * vec4(v_position, 1.0);

-    // z component of normal vector in world coordinate used for slope shading
-    world_normal_z = slope.actived ? (normalize(slope.volume_world_normal_matrix * v_normal)).z : 0.0;
+    // dot product of world normal with up direction, used for slope shading
+    world_normal_z = slope.actived ? dot(normalize(slope.volume_world_normal_matrix * v_normal), slope.up_direction) : 0.0;

    gl_Position = projection_matrix * position;
    if (is_outline) {
@@ -37,6 +37,7 @@ struct SlopeDetection
    bool actived;
 	 float normal_z;
    mat3 volume_world_normal_matrix;
+    vec3 up_direction;
 };
 uniform SlopeDetection slope;

@@ -85,7 +86,7 @@ void main()
              color = LightBlue;
              alpha = 1.0;
         }
-         else if( transformed_normal.z < slope.normal_z - EPSILON)
+         else if( dot(transformed_normal, slope.up_direction) < slope.normal_z - EPSILON)
        {
            color = color * 0.5 + LightRed * 0.5;
            alpha = 1.0;
@@ -24,6 +24,7 @@ struct SlopeDetection
    bool actived;
 	float normal_z;
    mat3 volume_world_normal_matrix;
+    vec3 up_direction;
 };
 uniform SlopeDetection slope;
 void main()
@@ -29,6 +29,7 @@ struct SlopeDetection
    bool actived;
 	float normal_z;
    mat3 volume_world_normal_matrix;
+    vec3 up_direction;
 };

 uniform vec4 uniform_color;
@@ -23,6 +23,7 @@ struct SlopeDetection
    bool actived;
 	float normal_z;
    mat3 volume_world_normal_matrix;
+    vec3 up_direction;
 };

 uniform mat4 view_model_matrix;
@@ -73,8 +74,8 @@ void main()
    // Point in homogenous coordinates.
    world_pos = volume_world_matrix * vec4(v_position, 1.0);

-    // z component of normal vector in world coordinate used for slope shading
-    world_normal_z = slope.actived ? (normalize(slope.volume_world_normal_matrix * v_normal)).z : 0.0;
+    // dot product of world normal with up direction, used for slope shading
+    world_normal_z = slope.actived ? dot(normalize(slope.volume_world_normal_matrix * v_normal), slope.up_direction) : 0.0;

    gl_Position = projection_matrix * position;
    if (is_outline) {
@@ -37,6 +37,7 @@ struct SlopeDetection
    bool actived;
 	 float normal_z;
    mat3 volume_world_normal_matrix;
+    vec3 up_direction;
 };
 uniform SlopeDetection slope;

@@ -87,7 +88,7 @@ void main()
              color = LightBlue;
              alpha = 1.0;
         }
-         else if( transformed_normal.z < slope.normal_z - EPSILON)
+         else if( dot(transformed_normal, slope.up_direction) < slope.normal_z - EPSILON)
        {
            color = color * 0.5 + LightRed * 0.5;
            alpha = 1.0;
@@ -24,6 +24,7 @@ struct SlopeDetection
    bool actived;
 	float normal_z;
    mat3 volume_world_normal_matrix;
+    vec3 up_direction;
 };
 uniform SlopeDetection slope;
 void main()
@@ -1549,6 +1549,7 @@
    "Flashforge/Generic PLA",
    "FlyingBear/Generic PLA",
    "Ginger Additive/Generic PLA",
+    "IdeaFormer/Generic PLA",
    "InfiMech/Generic PLA",
    "LONGER/Generic PLA",
    "Lulzbot/Generic PLA",
@@ -1556,6 +1557,7 @@
    "OrcaFilamentLibrary/Generic PLA",
    "Peopoly/Generic PLA",
    "Phrozen/Generic PLA",
+    "Printcepts/Generic PLA",
    "Prusa/Generic PLA",
    "Qidi/Generic PLA",
    "RH3D/Generic PLA",
@@ -4298,12 +4300,14 @@
    "Flashforge/Generic PETG",
    "FlyingBear/Generic PETG",
    "Ginger Additive/Generic PETG",
+    "IdeaFormer/Generic PETG",
    "InfiMech/Generic PETG",
    "LONGER/Generic PETG",
    "Lulzbot/Generic PETG",
    "OrcaArena/Generic PETG",
    "OrcaFilamentLibrary/Generic PETG",
    "Peopoly/Generic PETG",
+    "Printcepts/Generic PETG",
    "Prusa/Generic PETG",
    "Qidi/Generic PETG",
    "RH3D/Generic PETG",
@@ -5886,6 +5890,15 @@
   "filament_type": "PA-GF",
   "filament_vendor": "Eryone"
  },
+  "OFkrxQC4": {
+   "filaments": [
+    "IdeaFormer/eSUN PLA",
+    "Printcepts/eSUN PLA"
+   ],
+   "name": "eSUN PLA",
+   "filament_type": "PLA",
+   "filament_vendor": "eSUN"
+  },
  "OFks6esg": {
   "filaments": [
    "Creality/EN-PLA+"
@@ -91,6 +91,12 @@ if (SLIC3R_GUI)
 #    list(REMOVE_ITEM wxWidgets_LIBRARIES oleacc)

    find_package(wxInspector REQUIRED)
+    # wxInspector 1.0.0 installs its headers but accidentally declares the
+    # INSTALL_INTERFACE include directory PRIVATE, so its imported target does
+    # not expose them to consumers. Restore the package prefix include path until
+    # the upstream export is fixed.
+    get_filename_component(WXINSPECTOR_PREFIX "${wxInspector_DIR}/../../.." ABSOLUTE)
+    target_include_directories(wxInspector::wxInspector INTERFACE "${WXINSPECTOR_PREFIX}/include")

    # wxInspector's exported interface names the release wxWidgets import
    # libraries, which a Debug build cannot link. wx is linked above instead.
@@ -186,7 +192,7 @@ endif ()
 # Add the Slic3r GUI library, libcurl, OpenGL and GLU libraries.
 if (SLIC3R_GUI)
 #    target_link_libraries(OrcaSlicer ws2_32 uxtheme setupapi libslic3r_gui ${wxWidgets_LIBRARIES})
-target_link_libraries(OrcaSlicer libslic3r_gui)
+target_link_libraries(OrcaSlicer libslic3r_gui wxInspector::wxInspector)
    if (MSVC)
        # Generate debug symbols even in release mode.
        target_link_options(OrcaSlicer PUBLIC "$<$<CONFIG:RELEASE>:/DEBUG>")
@@ -1809,7 +1809,10 @@ int CLI::run(int argc, char **argv)
                        old_printable_width = static_cast<int>(old_printable_bbox.size().x());
                        old_printable_depth = static_cast<int>(old_printable_bbox.size().y());
                    }
-                    old_printable_height = (int)(config.opt_float("printable_height"));
+                    // A BBS-style 3mf without Metadata/project_settings.config has no
+                    // printable_height (found by fuzzing: this was a silent segfault).
+                    if (const auto *ph = config.option<ConfigOptionFloat>("printable_height"))
+                        old_printable_height = (int) ph->value;

                    if (config.option<ConfigOptionFloat>("extruder_clearance_height_to_rod"))
                        old_height_to_rod = config.opt_float("extruder_clearance_height_to_rod");
@@ -3341,9 +3344,14 @@ int CLI::run(int argc, char **argv)
                max_self_index = std::max(max_self_index, v);
                min_self_index = std::min(min_self_index, v);
            }
-            if (max_self_index > filament_count || min_self_index < 1) {
-                BOOST_LOG_TRIVIAL(warning) << boost::format("filament_self_index range [%1%, %2%] is invalid for filament_count %3%, regenerating")
-                        % min_self_index % max_self_index % filament_count;
+            // And a project saved with FEWER filaments than are now loaded (a
+            // one-filament project sliced with two --load-filaments) leaves the tables half filled:
+            // the variant matching below then reads past filament_extruder_variant and
+            // set_with_restore_2 throws an uncaught size error. Regenerate in that case too.
+            if (max_self_index > filament_count || min_self_index < 1 || max_self_index < filament_count
+                || (int) filament_self_index_opt->values.size() < filament_count) {
+                BOOST_LOG_TRIVIAL(warning) << boost::format("filament_self_index range [%1%, %2%] (size %4%) is invalid for filament_count %3%, regenerating")
+                        % min_self_index % max_self_index % filament_count % filament_self_index_opt->values.size();
                need_regenerate_self_index = true;
            }
        }
@@ -3424,6 +3432,10 @@ int CLI::run(int argc, char **argv)
                std::vector<string>& filament_variants = curr_variant_opt->values;
                filament_variants.resize(filament_count, get_extruder_variant_string(etDirectDrive, nvtStandard));
            }
+            // See the filament_self_index note above: one variant per filament for
+            // the filaments the project did not know about.
+            if ((int) curr_variant_opt->values.size() < filament_count)
+                curr_variant_opt->values.resize(filament_count, get_extruder_variant_string(etDirectDrive, nvtStandard));
            const ConfigOptionStrings *new_variant_opt = dynamic_cast<const ConfigOptionStrings*>(config.option("filament_extruder_variant", true));

            std::vector<int> new_variant_indice;
@@ -3432,7 +3444,7 @@ int CLI::run(int argc, char **argv)

            for (int i = 0; i < new_variant_count; i++)
            {
-                for (int j = old_start_indice[filament_index - 1]; j < old_start_indice[filament_index - 1] + old_variant_count; j++)
+                for (int j = old_start_indice[filament_index - 1]; j < old_start_indice[filament_index - 1] + old_variant_count && j < (int) curr_variant_opt->values.size(); j++)
                {
                    if (curr_variant_opt->values[j] == new_variant_opt->values[i]) {
                        new_variant_indice[i] = j;
@@ -3484,7 +3496,18 @@ int CLI::run(int argc, char **argv)
                                ConfigOptionVectorBase* opt_vec_dst = static_cast<ConfigOptionVectorBase*>(opt);
                                const ConfigOptionVectorBase* opt_vec_src = static_cast<const ConfigOptionVectorBase*>(source_opt);
                                //set with index
-                                opt_vec_dst->set_with_restore_2(opt_vec_src, new_variant_indice, old_start_indice[filament_index - 1], old_variant_count);
+                                try {
+                                    // A project with fewer filaments than are loaded: grow the
+                                    // destination to the filament's slot first (set_with_restore_2 only restores).
+                                    if (opt_vec_src->size() > 0 && opt_vec_dst->size() < size_t(old_start_indice[filament_index - 1] + old_variant_count))
+                                        opt_vec_dst->resize(size_t(old_start_indice[filament_index - 1] + old_variant_count), opt_vec_src);
+                                    opt_vec_dst->set_with_restore_2(opt_vec_src, new_variant_indice, old_start_indice[filament_index - 1], old_variant_count);
+                                } catch (const std::exception &ex) {   // Was an uncaught abort
+                                    BOOST_LOG_TRIVIAL(error) << boost::format("filament %1%: option %2% could not be applied: %3%") % filament_index % opt_key % ex.what();
+                                    boost::nowide::cerr << "filament " << filament_index << ": option " << opt_key << " could not be applied: " << ex.what() << std::endl;
+                                    record_exit_reson(outfile_dir, CLI_CONFIG_FILE_ERROR, 0, cli_errors[CLI_CONFIG_FILE_ERROR], sliced_info);
+                                    flush_and_exit(CLI_CONFIG_FILE_ERROR);
+                                }
                            }

                            continue;
@@ -3530,7 +3553,16 @@ int CLI::run(int argc, char **argv)
                    if (filament_options_with_variant.find(opt_key) != filament_options_with_variant.end()) {
                        std::vector<int> temp_variant_indice;
                        temp_variant_indice.resize(new_variant_count, -1);
-                        opt_vec_dst->set_with_restore_2(opt_vec_src, temp_variant_indice, old_start_indice[filament_index - 1], old_variant_count, true);
+                        try {
+                            if (opt_vec_src->size() > 0 && opt_vec_dst->size() < size_t(old_start_indice[filament_index - 1] + old_variant_count))   // See above
+                                opt_vec_dst->resize(size_t(old_start_indice[filament_index - 1] + old_variant_count), opt_vec_src);
+                            opt_vec_dst->set_with_restore_2(opt_vec_src, temp_variant_indice, old_start_indice[filament_index - 1], old_variant_count, true);
+                        } catch (const std::exception &ex) {   // Was an uncaught abort
+                            BOOST_LOG_TRIVIAL(error) << boost::format("filament %1%: option %2% could not be applied: %3%") % filament_index % opt_key % ex.what();
+                            boost::nowide::cerr << "filament " << filament_index << ": option " << opt_key << " could not be applied: " << ex.what() << std::endl;
+                            record_exit_reson(outfile_dir, CLI_CONFIG_FILE_ERROR, 0, cli_errors[CLI_CONFIG_FILE_ERROR], sliced_info);
+                            flush_and_exit(CLI_CONFIG_FILE_ERROR);
+                        }

                        if (opt_key == "filament_extruder_variant")
                            new_variant_counts[filament_index - 1] = opt_vec_src->size();
@@ -4014,6 +4046,10 @@ int CLI::run(int argc, char **argv)
        BOOST_LOG_TRIVIAL(info) << boost::format("%1%, set disable_wipe_tower_after_mapping back to false due to wrapping detect")%__LINE__;
    }

+    // Belt printers never get the classic wipe tower (see Print::has_wipe_tower()), so reserve no space for it.
+    const ConfigOptionBool* belt_printer_opt = m_print_config.option<ConfigOptionBool>("belt_printer");
+    const bool is_belt_printer = belt_printer_opt && belt_printer_opt->value;
+
    auto timelapse_type_opt = m_print_config.option("timelapse_type");
    bool is_smooth_timelapse = false;
    if (enable_timelapse && timelapse_type_opt && (timelapse_type_opt->getInt() == TimelapseType::tlSmooth))
@@ -4251,11 +4287,11 @@ int CLI::run(int argc, char **argv)
        }
    };

-    auto check_plate_wipe_tower = [get_print_sequence, is_smooth_timelapse](Slic3r::GUI::PartPlate* plate, int plate_index, DynamicPrintConfig& print_config, plate_obj_size_info_t &plate_obj_size_info) {
+    auto check_plate_wipe_tower = [get_print_sequence, is_smooth_timelapse, is_belt_printer](Slic3r::GUI::PartPlate* plate, int plate_index, DynamicPrintConfig& print_config, plate_obj_size_info_t &plate_obj_size_info) {
        plate_obj_size_info.obj_bbox= plate->get_objects_bounding_box();
        BOOST_LOG_TRIVIAL(info) << boost::format("plate %1%, object bbox: min {%2%, %3%, %4%} - max {%5%, %6%, %7%}")
                    %(plate_index+1) %plate_obj_size_info.obj_bbox.min.x() % plate_obj_size_info.obj_bbox.min.y() % plate_obj_size_info.obj_bbox.min.z() %plate_obj_size_info.obj_bbox.max.x() % plate_obj_size_info.obj_bbox.max.y() % plate_obj_size_info.obj_bbox.max.z();
-        if (!print_config.has("wipe_tower_x")) {
+        if (is_belt_printer || !print_config.has("wipe_tower_x")) {
            plate_obj_size_info.has_wipe_tower = false;
            BOOST_LOG_TRIVIAL(info) << boost::format("can not found wipe_tower_x in config, set to no wipe tower");
            return;
@@ -5062,7 +5098,7 @@ int CLI::run(int argc, char **argv)
                    }
                }

-                if ((!arrange_cfg.is_seq_print && (assemble_plate.filaments_count > 1))||(enable_wrapping_detect && !current_wrapping_exclude_area.empty()))
+                if (!is_belt_printer && ((!arrange_cfg.is_seq_print && (assemble_plate.filaments_count > 1)) || (enable_wrapping_detect && !current_wrapping_exclude_area.empty())))
                {
                    //prepare the wipe tower
                    int plate_count = partplate_list.get_plate_count();
@@ -5212,7 +5248,7 @@ int CLI::run(int argc, char **argv)
                bool is_seq_print = false;
                get_print_sequence(cur_plate, m_print_config, is_seq_print);

-                if (!is_seq_print && (assemble_plate.filaments_count > 1) && !has_wipe_tower_position)
+                if (!is_belt_printer && !is_seq_print && (assemble_plate.filaments_count > 1) && !has_wipe_tower_position)
                {
                    //prepare the wipe tower
                    auto printer_structure_opt = m_print_config.option<ConfigOptionEnum<PrinterStructure>>("printer_structure");
@@ -5361,7 +5397,7 @@ int CLI::run(int argc, char **argv)
                    //add the virtual object into unselect list if has
                    partplate_list.preprocess_exclude_areas(unselected, enable_wrapping_detect);

-                    if (used_filament_set.size() > 0)
+                    if (!is_belt_printer && used_filament_set.size() > 0)
                    {
                        //prepare the wipe tower
                        int plate_count = partplate_list.get_plate_count();
@@ -5467,7 +5503,7 @@ int CLI::run(int argc, char **argv)
                        BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << boost::format(": found single object mode");
                    }

-                    if (m_print_config.has("wipe_tower_x") && (is_smooth_timelapse || !arrange_cfg.is_seq_print || (selected.size() <= 1))) {
+                    if (!is_belt_printer && m_print_config.has("wipe_tower_x") && (is_smooth_timelapse || !arrange_cfg.is_seq_print || (selected.size() <= 1))) {
                        float x;
                        float y;
                        if (duplicate_count > 0) {
@@ -6037,7 +6073,7 @@ int CLI::run(int argc, char **argv)
                // The stored (or default) tower position may not fit the tower these plates
                // need, and no CLI placement site runs on a plain slice - mirror the GUI's
                // reload clamp and fit every plate's tower into the printable area first.
-                if (m_print_config.option<ConfigOptionBool>("enable_prime_tower", true)->value) {
+                if (!is_belt_printer && m_print_config.option<ConfigOptionBool>("enable_prime_tower", true)->value) {
                    for (int index = 0; index < partplate_list.get_plate_count(); index++) {
                        if ((plate_to_slice != 0) && (plate_to_slice != (index + 1)))
                            continue;
@@ -276,7 +276,13 @@ Points get_shrink_bedpts(const DynamicPrintConfig* print_cfg, const ArrangeParam
 template<class PConf>
 void fill_config(PConf& pcfg, const ArrangeParams &params) {

-        if (params.is_seq_print) {
+        if (params.is_belt) {
+            // Pack from the end of the belt that prints first.
+            pcfg.starting_point = !params.belt_reversed    ? PConf::Alignment::BOTTOM_LEFT :
+                                  params.belt_axis == 1    ? PConf::Alignment::TOP_LEFT :
+                                                             PConf::Alignment::BOTTOM_RIGHT;
+        }
+        else if (params.is_seq_print) {
            // Start placing the items from the center of the print bed
            pcfg.starting_point = PConf::Alignment::BOTTOM_LEFT;
        }
@@ -421,7 +427,51 @@ protected:
        return bindist;
    }

-    double dist_to_bin(const Box& ibb, const ClipperLib::IntPoint& origin_pack, typename Packer::PlacementConfig::Alignment starting_point_alignment)
+    // Belt printers pack from the end of the belt that prints first, and a corner
+    // packer's checks (pile inside the bin, pack origin) apply to them as well.
+    bool corner_packing() const { return params.is_belt || m_pconf.starting_point == PConfig::Alignment::BOTTOM_LEFT; }
+
+    static double at(const Box::PointType &pt, int i) { return double(i == 0 ? getX(pt) : getY(pt)); }
+
+    // Position along the belt in print order: increasing from the end that prints first.
+    double belt_pos(const Box::PointType &pt) const { return params.belt_reversed ? -at(pt, params.belt_axis) : at(pt, params.belt_axis); }
+    double belt_start(const Box &bb) const { return belt_pos(params.belt_reversed ? bb.maxCorner() : bb.minCorner()); }
+    double belt_end(const Box &bb) const { return belt_pos(params.belt_reversed ? bb.minCorner() : bb.maxCorner()); }
+
+    // The corner of the bin the belt pile grows from.
+    Box::PointType belt_origin() const
+    {
+        const Box bb = sl::boundingBox(m_bin);
+        auto o = bb.minCorner();
+        if (params.belt_reversed) {
+            if (params.belt_axis == 0) setX(o, getX(bb.maxCorner()));
+            else                       setY(o, getY(bb.maxCorner()));
+        }
+        return o;
+    }
+
+    // An item's far edge in print order is what it costs (so a row fills across the
+    // belt before the pile advances), with a slight pull toward the near lateral
+    // edge and the same penalty as the bottom-left heuristic for sitting outside
+    // the corner.
+    double dist_along_belt(const Box &ibb)
+    {
+        const Box    bin = sl::boundingBox(m_bin);
+        const int    l   = 1 - params.belt_axis;
+        const double lat = at(ibb.minCorner(), l) - at(bin.minCorner(), l);
+        double       d   = belt_end(ibb) - belt_start(bin);
+        d += lat < 0 ? 10 * -lat : 0.1 * lat;
+        if (double behind = belt_start(ibb) - belt_start(bin); behind < 0)
+            d += 10 * -behind;
+        return norm(d);
+    }
+
+    double corner_bindist(const Box &ibb, const ClipperLib::IntPoint &origin_pack)
+    {
+        return params.is_belt ? dist_along_belt(ibb) : dist_for_BOTTOM_LEFT(ibb, origin_pack);
+    }
+
+        double dist_to_bin(const Box& ibb, const ClipperLib::IntPoint& origin_pack, typename Packer::PlacementConfig::Alignment starting_point_alignment)
    {
        double bindist = 0;
        if (starting_point_alignment == PConfig::Alignment::BOTTOM_LEFT)
@@ -510,8 +560,8 @@ protected:

            // The smalles distance from the arranged pile center:
            double dist = norm(*(std::min_element(dists.begin(), dists.end())));
-            if (m_pconf.starting_point == PConfig::Alignment::BOTTOM_LEFT) {
-                double bindist = dist_for_BOTTOM_LEFT(ibb, origin_pack);
+            if (corner_packing()) {
+                double bindist = corner_bindist(ibb, origin_pack);
                score = 0.2 * dist + 0.8 * bindist;
            }
            else {
@@ -568,8 +618,8 @@ protected:
            break;
        }
        case LAST_BIG_ITEM: {
-            if (m_pconf.starting_point == PConfig::Alignment::BOTTOM_LEFT) {
-                score = dist_for_BOTTOM_LEFT(ibb, origin_pack);
+            if (corner_packing()) {
+                score = corner_bindist(ibb, origin_pack);
            }
            else {
                if (m_pilebb.defined)
@@ -584,8 +634,8 @@ protected:
            // already processed bigger items.
            // No need to play around with the anchor points, the center will be
            // just fine for small items
-            if (m_pconf.starting_point == PConfig::Alignment::BOTTOM_LEFT)
-                score = dist_for_BOTTOM_LEFT(ibb, origin_pack);
+            if (corner_packing())
+                score = corner_bindist(ibb, origin_pack);
            else {
                // Align mainly around existing items
                score = 0.8 * norm(pl::distance(ibb.center(), bigbb.center()))+ 0.2*norm(pl::distance(ibb.center(), origin_pack));
@@ -686,6 +736,28 @@ protected:
            score += 1 * (new_extruder_cnt-last_extruder_cnt);
        }

+        // On a belt the parts print in belt order, so every colour change between
+        // parts is a filament change. Items arrive sorted by extruder and the pile
+        // grows from the leading end; keep each colour's run contiguous by charging
+        // an item for every packed item of another colour it does not fully follow,
+        // counting the tilted layers that reach belt_tilt_slope * height past that
+        // item's far edge.
+        if (params.is_belt && !params.is_seq_print) {
+            const std::set<int> item_colours(item.extrude_ids.begin(), item.extrude_ids.end());
+            const double        item_start = belt_start(ibb);
+            for (Item &p : m_items) {
+                if (p.is_virt_object)
+                    continue;
+                const std::set<int> p_colours(p.extrude_ids.begin(), p.extrude_ids.end());
+                const bool same_colour = std::includes(item_colours.begin(), item_colours.end(), p_colours.begin(), p_colours.end())
+                                      || std::includes(p_colours.begin(), p_colours.end(), item_colours.begin(), item_colours.end());
+                if (same_colour)
+                    continue;
+                if (item_start < belt_end(p.boundingBox()) + scaled(p.height * params.belt_tilt_slope))
+                    score += 10.;
+            }
+        }
+
        return std::make_tuple(score, fullbb);
    }

@@ -762,7 +834,8 @@ public:

            auto binbb = sl::boundingBox(m_bin);

-            auto starting_point = cfg.starting_point == PConfig::Alignment::BOTTOM_LEFT ? binbb.minCorner() : binbb.center();
+            auto starting_point = this->params.is_belt ? belt_origin() :
+                cfg.starting_point == PConfig::Alignment::BOTTOM_LEFT ? binbb.minCorner() : binbb.center();
            // if we have wipe tower, items should be arranged around wipe tower
            for (Item itm : items) {
                if (itm.is_wipe_tower) {
@@ -913,7 +986,7 @@ std::function<double(const Item &, const ItemGroup&)> AutoArranger<ExPolygon>::g
        auto mp = m_merged_pile;
        mp.emplace_back(itm.transformedShape());
        auto chull = sl::convexHull(mp);
-        if (m_pconf.starting_point == PConfig::Alignment::BOTTOM_LEFT)
+        if (corner_packing())
        {
            if (!sl::isInside(chull, m_bin))
                score += LARGE_COST_TO_REJECT;
@@ -137,6 +137,13 @@ struct ArrangeParams {
    float nozzle_height = 0;
    float printable_height = 256.0;
    Vec2d align_center{ 0.5,0.5 };
+    // Belt printer: items print in the order they lie along the belt axis, from
+    // its low end unless belt_reversed, and a part's top prints
+    // belt_tilt_slope * height further along it than its base.
+    bool  is_belt         = false;
+    int   belt_axis       = 1;   // 0 = X, 1 = Y
+    bool  belt_reversed   = false;
+    float belt_tilt_slope = 1.f; // cot(belt tilt angle), 0 when the belt is not tilted

    ArrangePolygons excluded_regions;   // regions cant't be used
    ArrangePolygons nonprefered_regions; // regions can be used but not prefered
@@ -0,0 +1,536 @@
+#include <limits>
+#include "BeltBrim.hpp"
+
+#include "ClipperUtils.hpp"
+#include "Flow.hpp"
+#include "Layer.hpp"
+#include "Polygon.hpp"
+#include "Print.hpp"
+#include "ShortestPath.hpp"
+#include "Support/BeltFloorContext.hpp"
+
+#include <algorithm>
+
+namespace Slic3r {
+
+// ---------------------------------------------------------------- scaling
+
+static inline Point scale_u_point(const Point &p, int from_axis, double factor)
+{
+    // llround, not a cast: casting truncates toward zero, so a round trip would
+    // walk every vertex toward the origin by up to one unit per pass.
+    return from_axis == 0 ?
+        Point(coord_t(std::llround(double(p.x()) * factor)), p.y()) :
+        Point(p.x(), coord_t(std::llround(double(p.y()) * factor)));
+}
+
+static inline void scale_u_polygon(Polygon &poly, int from_axis, double factor)
+{
+    for (Point &p : poly.points)
+        p = scale_u_point(p, from_axis, factor);
+}
+
+ExPolygons belt_scale_u(const ExPolygons &src, const BeltBrimFrame &frame, double factor)
+{
+    ExPolygons out = src;
+    for (ExPolygon &ex : out) {
+        scale_u_polygon(ex.contour, frame.from_axis, factor);
+        for (Polygon &hole : ex.holes)
+            scale_u_polygon(hole, frame.from_axis, factor);
+    }
+    return out;
+}
+
+Polylines belt_scale_u(const Polylines &src, const BeltBrimFrame &frame, double factor)
+{
+    Polylines out = src;
+    for (Polyline &pl : out)
+        for (Point &p : pl.points)
+            p = scale_u_point(p, frame.from_axis, factor);
+    return out;
+}
+
+// ---------------------------------------------------------------- sweep
+
+ExPolygons sweep_ex(const ExPolygons &src, const Point &t)
+{
+    if (src.empty())
+        return {};
+    if (t == Point(0, 0))
+        return src;
+
+    // One parallelogram per boundary edge.  Together with P and P + t these
+    // cover the Minkowski sum exactly: for any q = p + s*t with p in P and
+    // s in [0, 1], let s* be the smallest lambda >= 0 with q - lambda*t in P.
+    // Either s* == 0 (so q is in P) or q - s* * t lies on some boundary edge e,
+    // putting q in that edge's parallelogram.  Hole edges must be included, or
+    // holes narrower than t along t would wrongly survive the sweep.
+    Polygons quads;
+    for (const ExPolygon &ex : src)
+        for (size_t c = 0; c < ex.num_contours(); ++ c)
+            for (const Line &e : ex.contour_or_hole(c).lines()) {
+                if (e.a == e.b)
+                    continue;
+                Polygon q;
+                q.points = { e.a, e.b, e.b + t, e.a + t };
+                // The non-zero fill rule counts a clockwise ring as -1, which
+                // would punch a hole instead of adding material.  Edges parallel
+                // to t give a zero-area quad; Clipper discards those harmlessly.
+                if (q.is_clockwise())
+                    q.reverse();
+                quads.emplace_back(std::move(q));
+            }
+
+    ExPolygons shifted = src;
+    for (ExPolygon &ex : shifted)
+        ex.translate(t);
+
+    // union_ex(ExPolygons, Polygons) uses pftNonZero, which is the fill rule the
+    // argument above relies on.
+    return union_ex(union_ex(src, shifted), quads);
+}
+
+// ---------------------------------------------------------------- brim region
+
+ExPolygons belt_brim_region(const ExPolygons    &footprint_flat,
+                            bool                 has_outer,
+                            bool                 has_inner,
+                            coord_t              brim_width,
+                            coord_t              object_gap,
+                            coord_t              leading,
+                            coord_t              lateral,
+                            const BeltBrimFrame &frame)
+{
+    if (footprint_flat.empty() || (! has_outer && ! has_inner))
+        return {};
+
+    ExPolygons out;
+
+    if (has_outer) {
+        // Offset the outer ring from the contours only, so a hole cannot punch
+        // through it.  Same reasoning as the plate brim in Brim.cpp.
+        Polygons contours;
+        contours.reserve(footprint_flat.size());
+        for (const ExPolygon &ex : footprint_flat)
+            contours.emplace_back(ex.contour);
+
+        // Inner and outer boundary offset from the same polygon, to avoid
+        // round-off mismatch between them.
+        ExPolygons inner = offset_ex(contours, float(object_gap), jtRound, SCALED_RESOLUTION);
+
+        // Close the interior before offsetting outwards.  A belt contact patch is often a
+        // narrow, broken-up strip, and the offset rings of two islands less than
+        // 2 x brim_width apart merge and fill the space between them - space that lies
+        // UNDER the part, which is not what "outer brim" means.  Closing also swallows
+        // holes in the patch for the same reason.  Concavity-filling only, so an apron or
+        // any other outward protrusion is untouched.
+        ExPolygons envelope = brim_width > 0 ? closing_ex(inner, float(brim_width)) : inner;
+
+        ExPolygons base  = envelope;
+        if (leading > 0) {
+            // Sweep downhill from the gapped keep-out, so the apron is contiguous with
+            // the ring instead of starting inside the gap.
+            const Point t = frame.from_axis == 0 ?
+                Point(frame.downhill_sign() * leading, 0) :
+                Point(0, frame.downhill_sign() * leading);
+            base = union_ex(base, sweep_ex(envelope, t));
+        }
+        if (lateral > 0) {
+            // Across the belt, both ways.  Swept from `base` so the apron is widened
+            // too, and in the flattened frame the cross-belt axis is unscaled, so this
+            // distance is already a true on-belt distance.
+            const Point t = frame.from_axis == 0 ? Point(0, lateral) : Point(lateral, 0);
+            ExPolygons widened = union_ex(sweep_ex(base, t), sweep_ex(base, Point(-t.x(), -t.y())));
+            base = union_ex(base, to_polygons(widened));
+        }
+        ExPolygons outer = offset_ex(base, float(brim_width), jtRound, SCALED_RESOLUTION);
+        expolygons_append(out, diff_ex(outer, envelope));
+    }
+
+    if (has_inner) {
+        // Holes reversed so a negative offset grows inward, mirroring Brim.cpp.
+        // No apron here: an apron growing into a hole interior is never useful.
+        Polygons holes;
+        for (const ExPolygon &ex : footprint_flat)
+            polygons_append(holes, ex.holes);
+        polygons_reverse(holes);
+        if (! holes.empty()) {
+            ExPolygons hole_inner = offset_ex(holes, - float(brim_width + object_gap));
+            ExPolygons hole_outer = offset_ex(holes, - float(object_gap));
+            expolygons_append(out, intersection_ex(diff_ex(hole_outer, hole_inner), holes));
+        }
+    }
+
+    return union_ex(out);
+}
+
+// ---------------------------------------------------------------- line lattice
+
+std::vector<coord_t> belt_brim_line_positions(coord_t u_lo,
+                                              coord_t u_hi,
+                                              coord_t pitch_u,
+                                              coord_t u_anchor)
+{
+    std::vector<coord_t> out;
+    if (pitch_u <= 0 || u_hi <= u_lo)
+        return out;
+
+    // Walk the lattice from just below u_lo.  Integer arithmetic throughout, so
+    // the half-open interval needs no epsilon: a point landing exactly on u_hi
+    // belongs to the next band.
+    int64_t k = int64_t(std::floor(double(u_lo - u_anchor) / double(pitch_u))) - 1;
+    while (u_anchor + coord_t(k) * pitch_u < u_lo)
+        ++ k;
+    for (;; ++ k) {
+        const coord_t u = u_anchor + coord_t(k) * pitch_u;
+        if (u >= u_hi)
+            break;
+        out.emplace_back(u);
+    }
+    return out;
+}
+
+// ---------------------------------------------------------------- pipeline
+
+// A band of the belt surface as an explicit box, clamped to `bounds` along the
+// shear axis.  Deliberately not BeltFloorContext::surface_polygon(): those
+// half-planes span +-1000 mm, which is wasteful to clip against and dangerous to
+// feed through the flattening scale.
+static Polygon band_box(const BoundingBox &bounds, int from_axis, coordf_t u_lo, coordf_t u_hi)
+{
+    coord_t lo = scale_(u_lo);
+    coord_t hi = scale_(u_hi);
+    const coord_t bmin = from_axis == 0 ? bounds.min.x() : bounds.min.y();
+    const coord_t bmax = from_axis == 0 ? bounds.max.x() : bounds.max.y();
+    lo = std::max(lo, bmin);
+    hi = std::min(hi, bmax);
+    Polygon poly;
+    if (hi <= lo)
+        return poly;
+    if (from_axis == 0)
+        poly.points = { Point(lo, bounds.min.y()), Point(hi, bounds.min.y()),
+                        Point(hi, bounds.max.y()), Point(lo, bounds.max.y()) };
+    else
+        poly.points = { Point(bounds.min.x(), lo), Point(bounds.max.x(), lo),
+                        Point(bounds.max.x(), hi), Point(bounds.min.x(), hi) };
+    return poly;
+}
+
+// Everything the per-band line generator needs, gathered once per object.
+struct BeltBrimContext
+{
+    BeltFloorContext ctx;
+    BeltBrimFrame    frame;
+    ExPolygons       region;      // brim region, object-local slicing XY
+    BoundingBox      region_bbox;
+    Flow             brim_flow;
+    coord_t          pitch_u   = 0;
+    coord_t          u_anchor  = 0;
+    double           in_plane_pitch = 0.;   // mm
+};
+
+// Emit the cross-belt brim lines that belong to the band [print_z - height, print_z].
+static void belt_brim_band_paths(const BeltBrimContext      &bc,
+                                 coordf_t                    print_z,
+                                 coordf_t                    height,
+                                 const Polygons             &obstacles,
+                                 ExtrusionEntityCollection  &out,
+                                 ExPolygons                 &areas_out)
+{
+    coordf_t u_lo = bc.ctx.cutoff_u(print_z - height);
+    coordf_t u_hi = bc.ctx.cutoff_u(print_z);
+    if (u_lo > u_hi)
+        std::swap(u_lo, u_hi);
+
+    // How wide this band is measured ON the belt, versus one nominal bead.
+    const double band_in_plane = (u_hi - u_lo) * bc.frame.u_stretch();
+
+    // Fraction of the layer height at which a line sits above the belt.  Toward the
+    // downhill edge, so the sheet is reasonably thick while the nozzle stays clear of
+    // the belt itself.
+    static constexpr double BAND_CLEARANCE_FRACTION = 0.75;
+
+    std::vector<coord_t> us;
+    double uniform_clearance = 0.;   // 0 => derive per line from its own position
+    double line_pitch        = bc.in_plane_pitch;
+    // One line also serves a band up to half a bead wider than the nominal pitch (a 0.3 mm
+    // first layer at 45 degrees): its flow is matched to the band, so the bead is that much
+    // wider. Two lattice lines in such a band would land almost on top of each other.
+    if (band_in_plane <= 1.5 * bc.in_plane_pitch + EPSILON) {
+        // Steep belt, which is the normal case: the band is narrower than one bead, so
+        // exactly one line fits.  Place it at a FIXED fraction of the band rather than
+        // on a nominal-spacing lattice.  On a lattice each line lands at an arbitrary
+        // point in its band, the clearance sweeps [0, height] from band to band, and the
+        // bead width therefore varies by 2x - visible as ragged, uneven brim lines.
+        // Anchoring to the band makes the clearance identical everywhere, so every bead
+        // is the same width.
+        //
+        // The spacing is then whatever the bands give (height / sin(tilt) on the belt)
+        // rather than the nominal bead spacing, so the flow below is matched to THAT
+        // pitch.  Matched flow at the real pitch is what keeps the sheet uniform and
+        // gap-free; using nominal flow at band spacing would over-feed it.
+        us.push_back(scale_(bc.ctx.cutoff_u(print_z - BAND_CLEARANCE_FRACTION * height)));
+        uniform_clearance = BAND_CLEARANCE_FRACTION * height;
+        line_pitch        = band_in_plane;
+    } else {
+        // Shallow belt: the band is wider than a bead, so it takes several lines and they
+        // have to sit on the nominal lattice.  Their clearances then differ, and so do
+        // their widths - unavoidable here, but shallow belts are the rare case.
+        us = belt_brim_line_positions(scale_(u_lo), scale_(u_hi), bc.pitch_u, bc.u_anchor);
+    }
+    if (us.empty())
+        return;
+
+    const Polygons region_polys = to_polygons(bc.region);
+
+    // One lattice line at a time: the clearance - and therefore the extrusion
+    // volume - is a property of the line's u, so the pieces of different lines
+    // must not be pooled before the flow is resolved.
+    // Overshoot the region so the clip, not the line's ends, decides the extent.
+    const coord_t margin = coord_t(SCALED_EPSILON) + 1;
+    coord_t       u_prev = std::numeric_limits<coord_t>::min();
+    for (coord_t u : us) {
+        // Nozzle-to-belt clearance for this line.  Constant along the line, because the
+        // belt height depends only on the shear-axis coordinate.  Band-anchored lines
+        // share one clearance by construction; lattice lines (shallow belts, or a first
+        // layer thick enough that the band is wider than a bead) each get their own.
+        //
+        // A lattice line can fall where the belt is only a hair below the band's print_z.
+        // The bead there would be laid scraping the belt while its flow is sized for a
+        // taller cell, so it is moved uphill to the same fraction of the band the
+        // single-line case uses.  (The clearance is along slice Z; the real gap under the
+        // nozzle is clearance x cos(tilt), 0.53 h at 45 degrees for the 0.75 fraction.)
+        double clearance = uniform_clearance;
+        if (clearance <= 0.) {
+            const Point probe = bc.frame.from_axis == 0 ? Point(u, 0) : Point(0, u);
+            clearance = print_z - bc.ctx.floor_print_z(probe);
+            if (clearance < BAND_CLEARANCE_FRACTION * height) {
+                clearance = BAND_CLEARANCE_FRACTION * height;
+                u         = scale_(bc.ctx.cutoff_u(print_z - clearance));
+            }
+            clearance = std::min(clearance, height);
+        }
+        // A line moved uphill can land on, or almost on, its neighbour; two beads closer
+        // than half a pitch would be laid into the same cell.
+        if (u_prev != std::numeric_limits<coord_t>::min() && std::abs(u - u_prev) < bc.pitch_u / 2)
+            continue;
+        u_prev = u;
+
+        Polyline line;
+        if (bc.frame.from_axis == 0)
+            line.points = { Point(u, coord_t(bc.region_bbox.min.y() - margin)),
+                            Point(u, coord_t(bc.region_bbox.max.y() + margin)) };
+        else
+            line.points = { Point(coord_t(bc.region_bbox.min.x() - margin), u),
+                            Point(coord_t(bc.region_bbox.max.x() + margin), u) };
+
+        Polylines pieces = intersection_pl(Polylines{ line }, region_polys);
+        if (! obstacles.empty())
+            pieces = diff_pl(pieces, obstacles);
+        if (pieces.empty())
+            continue;
+
+        // with_cross_section, not with_height: it reaches the prescribed volume while
+        // KEEPING the extrusion spacing, so the bead is sized to fill exactly one
+        // pitch x clearance cell of the sheet.
+        const Flow f = bc.brim_flow.with_cross_section(float(line_pitch * clearance));
+
+        // Footprint of these beads, for the first-layer convex hull and bbox.
+        for (const Polygon &p : offset(pieces, 0.5f * float(f.scaled_width())))
+            areas_out.emplace_back(ExPolygon(p));
+
+        extrusion_entities_append_paths(out.entities, chain_polylines(std::move(pieces)),
+                                        erBrim, f.mm3_per_mm(), f.width(), float(clearance));
+    }
+}
+
+// Union of everything extruded at `print_z` that the brim must keep clear of, expressed
+// in `self`'s local slicing frame.  Includes `self` itself: its slice at this Z can
+// overhang outside the belt footprint and land in the brim ring, which the flattened
+// brim_object_gap - a belt-plane separation - does not cover.
+//
+// THREADING: this runs inside posSupportMaterial, which Print::process() executes for all
+// objects in a tbb::parallel_for (Print.cpp).  Object slices are finished by then and safe
+// to read across objects, but SUPPORT layers are not: another object's thread may be
+// inside clear_support_layers() - which deletes the SupportLayer pointers - right now, so
+// touching a foreign object's support_layers() here is a use-after-free.  Only this
+// object's own supports are consulted; they are complete, because make_belt_brim() runs at
+// the tail of this object's own generate_support_material().  The cost is that the brim
+// does not dodge a *different* object's support at the same Z, which needs the objects to
+// overlap in the belt direction in the first place.
+// `region_bbox` bounds the brim; anything outside it cannot clip a brim line, so whole
+// objects are skipped without materialising their polygons.  On a typical plate the
+// objects do not overlap and every foreign object drops out here, which matters because
+// this runs once per band - hundreds of times per object.
+static Polygons belt_brim_obstacles(const Print &print, const PrintObject &self,
+                                    const BoundingBox &region_bbox, coordf_t print_z, coordf_t tol)
+{
+    const Point shift_self = self.instances().empty() ? Point(0, 0)
+                                                      : self.instances().front().shift_without_plate_offset();
+    Polygons out;
+    for (const PrintObject *o : print.objects()) {
+        const bool is_self = (o == &self);
+        for (const PrintInstance &inst : o->instances()) {
+            const Point delta = inst.shift_without_plate_offset() - shift_self;
+            if (const Layer *l = o->get_layer_at_printz(print_z, tol)) {
+                BoundingBox lb = get_extents(l->lslices);
+                lb.translate(delta.x(), delta.y());
+                if (lb.overlap(region_bbox)) {
+                    Polygons ps = to_polygons(l->lslices);
+                    for (Polygon &p : ps)
+                        p.translate(delta);
+                    polygons_append(out, std::move(ps));
+                }
+            }
+            if (! is_self)
+                continue;
+            if (const SupportLayer *sl = o->get_support_layer_at_printz(print_z, tol)) {
+                Polygons ps = sl->support_fills.polygons_covered_by_spacing();
+                for (Polygon &p : ps)
+                    p.translate(delta);
+                polygons_append(out, std::move(ps));
+            }
+        }
+    }
+    if (out.size() < 2)
+        return out;   // union_() of 0 or 1 polygons is pure overhead
+    return union_(out);
+}
+
+void make_belt_brim(PrintObject &object)
+{
+    object.clear_belt_brim();
+    if (! object.has_belt_brim())
+        return;
+
+    const Print &print = *object.print();
+    BeltBrimContext bc;
+    if (! bc.ctx.init(object.slicing_parameters(), print.config()))
+        return;
+    bc.frame = BeltBrimFrame{ bc.ctx.shear_factor(), bc.ctx.from_axis() };
+
+    const size_t nlayers = object.layers().size();
+    if (nlayers == 0)
+        return;
+
+    // 1. Belt footprint: the union of each layer's slice clipped to that layer's
+    //    own contact band.  This is the object's bottom face, which on a belt is
+    //    spread over every layer instead of sitting in layer 0.
+    ExPolygons footprint_acc;
+    for (size_t i = 0; i < nlayers; ++ i) {
+        const Layer &layer = *object.layers()[i];
+        if (layer.lslices.empty())
+            continue;
+        // print_z - height, not the previous layer's print_z: variable layer
+        // heights make the latter wrong.
+        coordf_t u_lo = bc.ctx.cutoff_u(layer.print_z - layer.height);
+        coordf_t u_hi = bc.ctx.cutoff_u(layer.print_z);
+        if (u_lo > u_hi)
+            std::swap(u_lo, u_hi);
+        BoundingBox bb = get_extents(layer.lslices);
+        bb.offset(scale_(1.));
+        const Polygon band = band_box(bb, bc.frame.from_axis, u_lo, u_hi);
+        if (band.empty())
+            continue;
+        expolygons_append(footprint_acc, intersection_ex(layer.lslices, Polygons{ band }));
+    }
+    const ExPolygons footprint = union_ex(footprint_acc);
+    if (footprint.empty())
+        return;
+
+    // 2. Brim region, offset in the flattened (true on-belt) metric.
+    const PrintObjectConfig &cfg = object.config();
+    bc.brim_flow = print.brim_flow();
+    const double  flow_w = bc.brim_flow.scaled_spacing() * SCALING_FACTOR;
+    // Quantize to an even number of lines, as the plate brim does.
+    const coord_t width   = scale_(std::floor(cfg.brim_width.value / flow_w / 2) * flow_w * 2);
+    const coord_t leading = scale_(cfg.leading_brim_length.value);
+    const coord_t lateral = scale_(cfg.extra_brim_width.value);
+    const coord_t gap     = scale_(cfg.brim_object_gap.value);
+
+    // Belt printers collapse Auto / Mouse ear / Painted to outer-only: the auto width
+    // heuristic and flat ear discs have no meaning on a tilted plane.  Leading-edge-only
+    // is an outer brim too; it is narrowed down to the first contact below.
+    const BrimType bt = cfg.brim_type.value;
+    const bool has_outer = bt == btOuterOnly || bt == btOuterAndInner
+                        || bt == btAutoBrim  || bt == btEar || bt == btPainted
+                        || bt == btLeadingEdgeOnly;
+    const bool has_inner = bt == btInnerOnly || bt == btOuterAndInner;
+
+    bc.region = belt_unflatten(
+        belt_brim_region(belt_flatten(footprint, bc.frame), has_outer, has_inner,
+                         width, gap, leading, lateral, bc.frame),
+        bc.frame);
+
+    if (bt == btLeadingEdgeOnly && ! bc.region.empty()) {
+        // Keep only what lies at or downhill of the object's FIRST contact with the
+        // belt, so the part is supported as it lands and nothing is printed alongside
+        // it afterwards.  The cut is the uphill edge of the first layer's contact band:
+        // everything past it belongs to later contacts.
+        const coordf_t u_cut   = bc.ctx.cutoff_u(object.layers().front()->print_z);
+        BoundingBox    keep_bb = get_extents(bc.region);
+        keep_bb.offset(scale_(1.));
+        const bool     low_side = bc.frame.shear > 0.;   // downhill is -u
+        const Polygon  keep = band_box(keep_bb, bc.frame.from_axis,
+            low_side ? unscale<double>(bc.frame.from_axis == 0 ? keep_bb.min.x() : keep_bb.min.y()) : u_cut,
+            low_side ? u_cut : unscale<double>(bc.frame.from_axis == 0 ? keep_bb.max.x() : keep_bb.max.y()));
+        bc.region = keep.empty() ? ExPolygons{} : intersection_ex(bc.region, Polygons{ keep });
+    }
+
+    if (bc.region.empty())
+        return;
+    bc.region_bbox = get_extents(bc.region);
+
+    // 3. Line lattice.  Fixed pitch in the flattened metric, anchored at the
+    //    footprint's leading-most edge so lines stay collinear across
+    //    disconnected islands and across the apron prologue.
+    bc.pitch_u = std::max<coord_t>(1, coord_t(bc.brim_flow.scaled_spacing() * bc.frame.cos_tilt()));
+    bc.in_plane_pitch = unscale<double>(bc.pitch_u) * bc.frame.u_stretch();
+    {
+        const BoundingBox fbb = get_extents(footprint);
+        const bool low_side = bc.frame.shear > 0.;
+        bc.u_anchor = bc.frame.from_axis == 0 ? (low_side ? fbb.min.x() : fbb.max.x())
+                                              : (low_side ? fbb.min.y() : fbb.max.y());
+    }
+
+    // 4. Bands coincident with an object layer.
+    std::vector<ExtrusionEntityCollection> by_layer(nlayers);
+    std::vector<ExPolygons>                areas_by_layer(nlayers);
+    for (size_t i = 0; i < nlayers; ++ i) {
+        const Layer &layer = *object.layers()[i];
+        const Polygons obstacles = belt_brim_obstacles(print, object, bc.region_bbox, layer.print_z, 0.5 * layer.height);
+        belt_brim_band_paths(bc, layer.print_z, layer.height, obstacles, by_layer[i], areas_by_layer[i]);
+    }
+
+    // 5. Apron prologue: the part of the region downhill of the object's first
+    //    layer, which has no object layer to ride on.
+    std::vector<BeltBrimBand> prologue;
+    {
+        const Layer   &first  = *object.layers().front();
+        const coordf_t h      = first.height;
+        const bool     low_side = bc.frame.shear > 0.;
+        const coord_t  u_lead_s = bc.frame.from_axis == 0
+            ? (low_side ? bc.region_bbox.min.x() : bc.region_bbox.max.x())
+            : (low_side ? bc.region_bbox.min.y() : bc.region_bbox.max.y());
+        const coordf_t u_lead  = unscale<double>(u_lead_s);
+        // print_z at which the belt surface crosses the region's leading edge.
+        const coordf_t z_lead  = bc.ctx.shear_factor() * u_lead
+                               + bc.ctx.floor_offset() + bc.ctx.z_shift();
+        if (h > EPSILON)
+            for (coordf_t z = first.print_z - h; z > z_lead - h; z -= h) {
+                const Polygons obstacles = belt_brim_obstacles(print, object, bc.region_bbox, z, 0.5 * h);
+                BeltBrimBand band;
+                band.print_z = z;
+                band.height  = h;
+                belt_brim_band_paths(bc, z, h, obstacles, band.fills, band.areas);
+                if (! band.fills.empty())
+                    prologue.emplace_back(std::move(band));
+            }
+        // Lowest Z first, so collect_layers_to_print sees them in print order.
+        std::reverse(prologue.begin(), prologue.end());
+    }
+
+    object.set_belt_brim(std::move(by_layer), std::move(areas_by_layer), std::move(prologue));
+}
+
+} // namespace Slic3r
@@ -0,0 +1,169 @@
+#ifndef slic3r_BeltBrim_hpp_
+#define slic3r_BeltBrim_hpp_
+
+#include "ExPolygon.hpp"
+#include "ExtrusionEntityCollection.hpp"
+#include "Point.hpp"
+#include "Polyline.hpp"
+
+#include <cmath>
+#include <vector>
+
+// Belt-printer brim geometry.
+//
+// A belt printer slices in a ROTATED frame, so the belt surface is not the
+// Z=0 bed plane but a tilted plane in slicing space:
+//
+//     z_slicing(u) = shear * u + floor_offset + z_shift,   u = X or Y
+//
+// where `shear == tan(tilt)` (SlicingParameters::belt_floor_shear_factor) and
+// the axis is selected by SlicingParameters::belt_floor_from_axis.  See
+// Support/BeltFloorContext.hpp for the canonical accessors.
+//
+// Consequences that drive everything in this file:
+//
+//   * A horizontal slicing layer touches the belt only along a narrow strip at
+//     its leading edge, `layer_height / shear` wide (~0.2 mm at 45 degrees).
+//     The object's belt footprint - its bottom face - is therefore spread over
+//     every layer, not contained in layer 0.
+//   * Distances measured in slicing XY are NOT on-belt distances: moving `du`
+//     along the shear axis travels `du / cos(tilt)` across the belt.  So brim
+//     offsets have to be taken in a "flattened" space where the shear axis is
+//     stretched by `1 / cos(tilt)`, then mapped back.
+//   * Brim ahead of the part (downhill) lies at slicing Z BELOW the object's
+//     first layer, because the object's layer 0 is precisely its leading
+//     contact with the belt.
+//
+// Everything here is pure geometry on ExPolygons/Polylines so it can be unit
+// tested without a Print.  Keep user-visible strings out of this file: it is
+// not listed in localization/i18n/list.txt.
+
+namespace Slic3r {
+
+// Tilt window within which the BELT plane, not the bed plane, is the adhesion
+// surface.  Below ~1 degree a belt is a flat bed as far as adhesion goes, and the
+// contact band would be layer_height/sin(tilt) - tens of millimetres - so the
+// ordinary plate brim is both correct and cheaper.  Above ~85 degrees the whole
+// brim compresses into a sliver and is not worth generating.
+inline constexpr double BELT_BRIM_MIN_TILT_DEG = 1.;
+inline constexpr double BELT_BRIM_MAX_TILT_DEG = 85.;
+
+// Description of the tilted belt plane, reduced to what the brim geometry needs.
+struct BeltBrimFrame
+{
+    // tan(tilt).  Sign selects which way is downhill.
+    double shear     = 0.;
+    // 0 = X, 1 = Y.  Matches BeltFloorContext::from_axis().
+    int    from_axis = 1;
+
+    // 1 / cos(tilt).  Stretch factor that turns a projected distance along
+    // `from_axis` into the true distance travelled across the belt.
+    double u_stretch() const { return std::sqrt(1. + shear * shear); }
+    // cos(tilt).  The inverse mapping.
+    double cos_tilt()  const { return 1. / this->u_stretch(); }
+    // Downhill is where the belt surface is lower, i.e. printed earlier, i.e.
+    // the leading edge of the part.  For shear > 0 that is -u.
+    int    downhill_sign() const { return shear > 0. ? -1 : +1; }
+};
+
+// Scale only the `from_axis` component by `factor`, rounding to nearest.
+//
+// Deliberately not MultiPoint::scale(fx, fy) / ExPolygon::scale(fx, fy): those
+// truncate toward zero, which is asymmetric about the origin and loses up to a
+// full coordinate unit per vertex on every round trip.
+ExPolygons belt_scale_u(const ExPolygons &src, const BeltBrimFrame &frame, double factor);
+Polylines  belt_scale_u(const Polylines  &src, const BeltBrimFrame &frame, double factor);
+
+// Into / out of the space where Euclidean offsets equal true on-belt distances.
+inline ExPolygons belt_flatten(const ExPolygons &src, const BeltBrimFrame &frame)
+    { return belt_scale_u(src, frame, frame.u_stretch()); }
+inline ExPolygons belt_unflatten(const ExPolygons &src, const BeltBrimFrame &frame)
+    { return belt_scale_u(src, frame, frame.cos_tilt()); }
+
+// Minkowski sum of `src` with the segment [0, t]: the region swept by sliding
+// `src` along t.  Used to grow the brim downhill for "extra brim width".
+//
+// Implemented as union_(P, P + t, {parallelogram per boundary edge}) over ALL
+// contours including holes, with every parallelogram forced counter-clockwise
+// so the non-zero fill rule closes holes narrower than t along the sweep
+// direction.  A hole survives exactly when it is wider than |t| measured along
+// t - not when it is wider in its narrowest Euclidean direction.
+ExPolygons sweep_ex(const ExPolygons &src, const Point &t);
+
+// Brim region for one already-flattened belt footprint.  All lengths are scaled
+// and measured in the flattened (true on-belt) metric.
+//
+// `has_outer` / `has_inner` are the resolved BrimType: belt printers collapse
+// Auto / Mouse ear / Painted to outer-only, so the caller does that mapping and
+// this function never needs PrintConfig.
+//
+// Two directional extras are applied to the footprint before the outer offset, so
+// each one buys reach in one direction only:
+//
+//   `leading` (leading_brim_length) sweeps the footprint DOWNHILL along the belt,
+//   so every leading-facing edge gains an apron ahead of it.
+//   `lateral`  (extra_brim_width)   sweeps it BOTH WAYS across the belt, widening
+//   the brim sideways without pushing it further ahead or behind.
+//
+// Neither is applied to the inner (hole) ring.
+ExPolygons belt_brim_region(const ExPolygons   &footprint_flat,
+                            bool                has_outer,
+                            bool                has_inner,
+                            coord_t             brim_width,
+                            coord_t             object_gap,
+                            coord_t             leading,
+                            coord_t             lateral,
+                            const BeltBrimFrame &frame);
+
+// Brim line positions for one layer band.
+//
+// Lines sit on a fixed lattice `u_anchor + k * pitch_u` so the on-belt spacing
+// between neighbouring brim lines is constant regardless of how the lattice
+// falls across layer bands.  Snapping to band centres instead would quantise
+// the spacing to whole bands and under-deposit by ~35% at 45 degrees.
+//
+// The band is half-open, [u_lo, u_hi), so every lattice point belongs to
+// exactly one band: none duplicated at a boundary, none dropped.  A band
+// narrower than the pitch simply yields nothing; a band much wider (shallow
+// tilt) yields several lines.
+std::vector<coord_t> belt_brim_line_positions(coord_t u_lo,
+                                              coord_t u_hi,
+                                              coord_t pitch_u,
+                                              coord_t u_anchor);
+
+// ---------------------------------------------------------------- pipeline
+
+// One brim-only layer printed BEFORE the object's first layer, carrying the
+// apron that has to be stuck to the belt ahead of the part.
+//
+// Deliberately not a Layer subclass.  A synthetic Layer would inherit id()
+// semantics that leak into initial-layer temperature selection, the spiral vase
+// probe, gradual interpolation, avoid-crossing-perimeters and cooling, all of
+// which key off Layer::id() == 0 or off a layer's regions.  A plain record
+// carries only what the emitter needs.
+//
+// `height` is the LAYER height, used for the Z move and ordering metadata only.
+// Each extrusion path inside `fills` carries its own height, equal to that
+// line's nozzle-to-belt clearance, which varies across the band.
+struct BeltBrimBand
+{
+    coordf_t                  print_z = 0.;
+    coordf_t                  height  = 0.;
+    // erBrim paths in the object's local slicing frame, untranslated.
+    ExtrusionEntityCollection fills;
+    // Footprint of those paths, for the first-layer convex hull / bbox.
+    ExPolygons                areas;
+};
+
+class PrintObject;
+
+// Generate the belt brim for one object: fills its per-object-layer bands and
+// its apron prologue.  No-op unless PrintObject::has_belt_brim().
+//
+// Runs inside posSupportMaterial rather than the brim step, because the prologue
+// print_z values must exist before ToolOrdering is built at psWipeTower.
+void make_belt_brim(PrintObject &object);
+
+} // namespace Slic3r
+
+#endif // slic3r_BeltBrim_hpp_
@@ -0,0 +1,73 @@
+#include "BeltGCode.hpp"
+#include "GCodeWriter.hpp"
+#include "GCode/BeltKinematics.hpp"
+#include "BeltTransform.hpp"
+#include "Print.hpp"
+
+namespace Slic3r {
+
+void BeltGCode::init_belt_writer(Print &print)
+{
+    auto belt_writer = std::make_unique<GCodeWriter>();
+    // Axis remap and build volume max are set by base GCode after init_belt_writer
+    // returns; set_kinematics() replays them, so install order does not matter.
+    install_belt_kinematics(*belt_writer, print.config());
+    belt_writer->set_force_normal_lift(true);
+    // The plate origin was stored on the writer this one replaces.
+    belt_writer->set_xy_offset(m_gcode_offset.x(), m_gcode_offset.y());
+    m_writer = std::move(belt_writer);
+}
+
+void BeltGCode::write_belt_header(GCodeOutputStream &file, const Print &print)
+{
+    const auto &full_cfg = print.full_print_config();
+    // Slicing rotation: the belt tilt (axis + angle) and the single source of truth
+    // for the physical tilt the G-code viewer uses to enable belt view.
+    file.write_format("; belt_slice_rotation = %s\n", full_cfg.opt_serialize("belt_slice_rotation").c_str());
+    file.write_format("; belt_slice_rotation_angle = %.1f\n", print.config().belt_slice_rotation_angle.value);
+    file.write_format("; belt_slice_rotation_global = %d\n", print.config().belt_slice_rotation_global.value ? 1 : 0);
+    // Pre-slice remap configs
+    file.write_format("; preslice_remap_x = %s\n", full_cfg.opt_serialize("preslice_remap_x").c_str());
+    file.write_format("; preslice_remap_y = %s\n", full_cfg.opt_serialize("preslice_remap_y").c_str());
+    file.write_format("; preslice_remap_z = %s\n", full_cfg.opt_serialize("preslice_remap_z").c_str());
+    file.write_format("; preslice_remap_global = %d\n", print.config().preslice_remap_global.value ? 1 : 0);
+    file.write_format("; belt_preslice_global = %d\n", print.config().belt_preslice_global.value ? 1 : 0);
+    // Machine-frame transform: shear (tan) + scale (1/cos) derived from the belt
+    // tilt angle (or belt_frame_tilt_angle when decoupled).
+    file.write_format("; belt_frame_tilt_decouple = %d\n", print.config().belt_frame_tilt_decouple.value ? 1 : 0);
+    file.write_format("; belt_frame_tilt_angle = %.1f\n", print.config().belt_frame_tilt_angle.value);
+}
+
+void BeltGCode::on_set_origin(const PrintObject * /*obj*/, const Point & /*inst_shift*/)
+{
+    // Global pre-slice mode: adjust origin using computed correction.
+    // Transform the origin through the belt pipeline so that
+    // back_transform(T * origin) = origin (correct machine position).
+    //
+    // Flags that trigger this path:
+    //   belt_preslice_global         — full pipeline (rotation * remap) is global
+    //   preslice_remap_global        — only the pre-slice remap is global
+    //   belt_slice_rotation_global   — slicing rotation treated as global (matches
+    //                                  the per-instance Z-offset added in PrintObjectSlice.cpp)
+    // The XY origin adjustment uses the FULL forward transform, because the
+    // back_transform applied during G-code emission is always the inverse of
+    // the full pipeline.
+    bool use_global = m_config.belt_preslice_global.value
+        || (m_config.preslice_remap_global.value
+            && BeltTransformPipeline::has_preslice_remap(m_config))
+        || (m_config.belt_slice_rotation_global.value
+            && m_config.belt_slice_rotation.value != BeltRotationAxis::None
+            && std::abs(m_config.belt_slice_rotation_angle.value) > EPSILON);
+    if (!use_global)
+        return;
+
+    // Adjust origin: transform through belt forward pipeline so that
+    // the back-transform correctly recovers model-space positions.
+    Transform3d T = BeltTransformPipeline::build_forward_transform(m_config);
+    Vec2d cur_origin = this->origin();
+    Vec3d origin3d(cur_origin.x(), cur_origin.y(), 0.);
+    Vec3d adjusted = T.linear() * origin3d;
+    this->set_origin(Vec2d(adjusted.x(), adjusted.y()));
+}
+
+} // namespace Slic3r
@@ -0,0 +1,23 @@
+#pragma once
+
+#include "GCode.hpp"
+
+namespace Slic3r {
+
+// Belt-printer-specific GCode export.
+//
+// Inherits from GCode and overrides virtual hooks to:
+// - Install a BeltKinematics on the GCodeWriter
+// - Write belt configuration to the G-code header
+// - Adjust the origin for global pre-slice transforms when switching instances
+// (Arc fitting is disabled for belt printers by BeltKinematics::supports_arc_moves(),
+//  which the base GCode::should_disable_arc_fitting() consults -- no override needed.)
+class BeltGCode : public GCode
+{
+protected:
+    void init_belt_writer(Print &print) override;
+    void write_belt_header(GCodeOutputStream &file, const Print &print) override;
+    void on_set_origin(const PrintObject *obj, const Point &inst_shift) override;
+};
+
+} // namespace Slic3r
@@ -0,0 +1,417 @@
+// ORCA-Belt: backend of the belt purge tower (the belt replacement for the
+// classic wipe/prime tower).
+//
+// Kept in its own translation unit so the belt-purge logic stays out of the way
+// of unrelated upstream changes to Print.cpp / PrintObjectSlice.cpp and carries
+// no regression risk for normal printers: none of these methods do anything
+// unless the print is a belt printer with the belt purge tower enabled.
+//
+//   Print::has_belt_purge_tower()      - is the belt purge tower active?
+//   Print::_align_belt_purge_layers()  - snap the prism's layer grid onto the
+//                                        printed objects' grid
+//   Print::_plan_belt_purge()          - route filament-change purging into the
+//                                        prism (flush-into-objects), no wipe tower
+//   PrintObject::belt_shift_layer_grid()      - shift a sliced layer grid
+//   PrintObject::belt_truncate_layers_above() - cancel the prism past the last swap
+//
+// (Declarations live in Print.hpp alongside the rest of the Print interface.)
+
+#include "Print.hpp"
+#include "PrintConfig.hpp"
+#include "Exception.hpp"
+#include "GCode/ToolOrdering.hpp"
+#include "Layer.hpp"
+#include "ExtrusionEntity.hpp"
+#include "ExtrusionEntityCollection.hpp"
+#include "I18N.hpp"
+#include "format.hpp"
+#include "LocalesUtils.hpp"
+#include "libslic3r.h"
+
+#include <algorithm>
+#include <cmath>
+#include <limits>
+
+#include <boost/log/trivial.hpp>
+
+namespace Slic3r {
+
+// Belt purge prism: purging after filament changes is routed into a sliced
+// prism object via the flush-into-objects machinery instead of a wipe tower.
+bool Print::has_belt_purge_tower() const
+{
+    // Its own purge-tower "type", gated by the belt-only enable_belt_purge_tower
+    // option (not the classic enable_prime_tower).
+    if (!(m_config.belt_printer.value
+          && m_config.enable_belt_purge_tower.value
+          && !m_config.spiral_mode.value
+          && m_config.filament_diameter.values.size() > 1))
+        return false;
+
+    return std::any_of(m_objects.begin(), m_objects.end(), [](const PrintObject *object) {
+        return object->config().belt_purge_tower_object.value;
+    });
+}
+
+// Belt mode: align ALL objects on the plate (the printed objects AND the purge
+// prism) onto one common layer grid, so the prism can absorb every toolchange.
+//
+// After belt slicing each object's layer print_z carries a per-object global z
+// offset (mesh-vertex-scan belt_z_shift + instance-Y-dependent terms), so
+// objects at different belt-Y positions get layer grids with DIFFERENT residues
+// (mod layer height). Purge marking looks absorbers up with
+// get_layer_at_printz(lt.print_z, EPSILON), so a toolchange on object B only
+// absorbs into the prism if the prism has a layer at B's print_z. Snapping only
+// the prism to one object therefore worked for a single (assembled) multi-color
+// object but failed with multiple separate objects — the prism could follow only
+// one grid, and toolchanges on the others went unabsorbed ("multiple layer
+// grids" warning).
+//
+// Fix: pick one reference grid (the tallest object) and shift every object onto
+// it. Each shift is at most half a layer height — a sub-100µm move along the
+// belt, the very same mechanism the per-object global_z_offset already uses, and
+// it keeps each object internally consistent (belt_shift_layer_grid moves the
+// object's layers, its support layers, and its belt floor together). Equal layer
+// height across objects is enforced by Print::validate(), so once residues match
+// every object steps on the same lattice {ref_offset + k*h} and every toolchange
+// layer coincides with a prism layer.
+void Print::_align_belt_purge_layers()
+{
+    PrintObject *prism = nullptr;
+    for (PrintObject *po : m_objects)
+        if (po->config().belt_purge_tower_object.value && !po->layers().empty()) {
+            prism = po;
+            break;
+        }
+    if (prism == nullptr || prism->layers().empty())
+        return;
+
+    const double h = prism->config().layer_height.value;
+    if (h <= EPSILON)
+        return;
+
+    // Grid residue of an object's layer grid: identical for all of an object's
+    // layers above the first since they step by h.
+    auto grid_offset = [h](const PrintObject *po) -> double {
+        if (po->layers().empty())
+            return 0.;
+        const double z = po->layers().front()->print_z;
+        return z - std::floor(z / h) * h; // in [0, h)
+    };
+
+    // Reference grid: the tallest non-prism object (proxy for the object with
+    // the most toolchange layers — minimizes how far the rest must move).
+    const PrintObject *ref     = nullptr;
+    double             ref_top = -std::numeric_limits<double>::max();
+    for (const PrintObject *po : m_objects) {
+        if (po->config().belt_purge_tower_object.value || po->layers().empty())
+            continue;
+        const double top = po->layers().back()->print_z;
+        if (top > ref_top) {
+            ref_top = top;
+            ref     = po;
+        }
+    }
+    if (ref == nullptr)
+        return;
+
+    const double ref_offset = grid_offset(ref);
+
+    // Snap every object (printed objects AND the prism) onto the reference grid.
+    for (PrintObject *po : m_objects) {
+        if (po->layers().empty())
+            continue;
+        double delta = ref_offset - grid_offset(po);
+        if (delta > 0.5 * h)
+            delta -= h;
+        else if (delta <= -0.5 * h)
+            delta += h;
+        po->belt_shift_layer_grid(delta); // no-op for the reference object (delta ~ 0)
+    }
+}
+
+// Belt mode replacement for _make_wipe_tower(): plan filament-change purging
+// into the belt purge prism (and any other flush_into_* object) using the
+// flush-into-objects machinery, without generating classic wipe tower G-code.
+// The toolchange itself is emitted by GCode::set_extruder() via the
+// change_filament_gcode macro; the overrides marked here make the new
+// filament's first extrusions land in the purge prism.
+void Print::_plan_belt_purge()
+{
+    m_wipe_tower_data.clear();
+
+    // psWipeTower may be invalidated without posSlice (for example after a
+    // filament-map or tool-ordering change). Restore a prism shortened by the
+    // previous plan so a newly higher toolchange can use its original layers.
+    for (PrintObject *po : m_objects)
+        if (po->config().belt_purge_tower_object.value)
+            po->belt_undo_purge_plan();
+
+    // Must run before ToolOrdering is built: LayerTools merge per-object layer
+    // print_z values, and the prism only absorbs purge where its (snapped)
+    // layers coincide with the toolchange layers.
+    this->_align_belt_purge_layers();
+
+    const unsigned int number_of_extruders = (unsigned int) m_config.filament_colour.values.size();
+
+    // No initial priming extrusions: there is no tower to prime on.
+    m_wipe_tower_data.tool_ordering = ToolOrdering(*this, (unsigned int) -1, false);
+    m_wipe_tower_data.tool_ordering.sort_and_build_data(*this, (unsigned int) -1, false);
+
+    if (m_wipe_tower_data.tool_ordering.empty() || m_wipe_tower_data.tool_ordering.last_extruder() == unsigned(-1))
+        throw Slic3r::SlicingError("The print is empty. The model is not printable with current print settings.");
+
+    // Is there any filament change at all? Not ToolOrdering::has_wipe_tower(): that reads the
+    // FIRST layer's flag, and on a belt the first layer may be a brim apron band, which carries
+    // neither object nor support and so never gets the flag even when the print changes filament.
+    {
+        bool         any_change = false;
+        unsigned int cur        = m_wipe_tower_data.tool_ordering.first_extruder();
+        for (const auto &lt : m_wipe_tower_data.tool_ordering.layer_tools())
+            for (const unsigned int e : lt.extruders)
+                if (e != cur) { any_change = true; cur = e; }
+        if (! any_change)
+            return;
+    }
+
+    this->throw_if_canceled();
+
+    // Flush volumes per filament pair, mirroring the generic wipe tower path:
+    // full flush matrix for single extruder multi material with purging enabled,
+    // plain prime volume otherwise.
+    std::vector<float> flush_matrix(cast<float>(
+        get_flush_volumes_matrix(m_config.flush_volumes_matrix.values, 0, m_config.nozzle_diameter.values.size())));
+    std::vector<std::vector<float>> wipe_volumes;
+    for (unsigned int i = 0; i < number_of_extruders; ++i)
+        wipe_volumes.push_back(std::vector<float>(flush_matrix.begin() + i * number_of_extruders,
+                                                  flush_matrix.begin() + (i + 1) * number_of_extruders));
+    const bool  use_flush_matrix = m_config.purge_in_prime_tower && m_config.single_extruder_multi_material;
+    const float flush_multiplier = (float) m_config.flush_multiplier.get_at(0);
+
+    // Cancel the purge prism early: pre-scan the tool ordering for the highest
+    // print_z that actually has a toolchange, then drop the prism's layers above
+    // it so the tower stops at the last color swap (saves filament/time). This
+    // MUST happen before the marking loop below: ensure_perimeters_infills_order
+    // force-overrides the prism's extrusions on every layer (it is a dedicated
+    // flush object), so truncating afterwards would leave dangling overrides
+    // pointing into deleted layers.
+    {
+        // The tool ordering covers the WHOLE print, and the prism is a printed
+        // object in it. Left unbounded, the scan below sees the prism's own
+        // toolchanges on layers above every model object -- the prism runs past
+        // them by design (ramp/height compensation at the tilted ends) -- so
+        // last_tc_z lands at the prism's own top and the truncation cancels
+        // nothing. The tower ends up justifying its own existence.
+        //
+        // Nothing above the tallest printed object can require a color change,
+        // so bound the scan there. On MCTEST5 that is 197 toolchanges spanning
+        // z=154.00..193.20 with the tallest object topping out at 153.80, i.e.
+        // 39.4 mm of tower that no swap ever needed.
+        // Support layers count too: on a belt they can extend above the object's
+        // own top, and a toolchange there is a real one.
+        double obj_top_z = -1.;
+        for (const PrintObject *po : m_objects) {
+            if (po->config().belt_purge_tower_object.value)
+                continue;
+            if (!po->layers().empty())
+                obj_top_z = std::max(obj_top_z, po->layers().back()->print_z);
+            if (!po->support_layers().empty())
+                obj_top_z = std::max(obj_top_z, po->support_layers().back()->print_z);
+        }
+
+        double       last_tc_z   = -1.;
+        unsigned int cur_ext     = m_wipe_tower_data.tool_ordering.first_extruder();
+        for (const auto &lt : m_wipe_tower_data.tool_ordering.layer_tools()) {
+            // layer_tools() is ordered by print_z ascending.
+            if (obj_top_z >= 0. && lt.print_z > obj_top_z + EPSILON)
+                break;
+            for (const unsigned int e : lt.extruders)
+                if (e != cur_ext) { last_tc_z = lt.print_z; cur_ext = e; }
+        }
+        // Deliberately NOT cancelling the prism outright when no object toolchange
+        // exists: belt_truncate_layers_above(0.) empties m_layers, and an object
+        // with zero layers is not something the rest of the pipeline expects. The
+        // GUI already declines to create a prism unless more than one filament is
+        // in use, so this case is a stale prism, not a hot path -- leave it whole
+        // rather than risk a zero-layer object.
+        if (last_tc_z >= 0.)
+            for (PrintObject *po : m_objects)
+                if (po->config().belt_purge_tower_object.value && !po->layers().empty()) {
+                    po->belt_truncate_layers_above(last_tc_z);
+                    break;
+                }
+    }
+
+    // The prism only absorbs purge at toolchange layers whose print_z coincides
+    // with one of its own layers.
+    PrintObject *prism_po = nullptr;
+    for (PrintObject *po : m_objects)
+        if (po->config().belt_purge_tower_object.value && !po->layers().empty()) { prism_po = po; break; }
+
+    float  total_leftover      = 0.f;
+    float  worst_layer_leftover = 0.f;
+    double worst_layer_z       = 0.;
+
+    unsigned int current_extruder_id = m_wipe_tower_data.tool_ordering.first_extruder();
+    for (auto &layer_tools : m_wipe_tower_data.tool_ordering.layer_tools()) {
+        float layer_leftover = 0.f;
+        for (const unsigned int extruder_id : layer_tools.extruders) {
+            if (extruder_id == current_extruder_id)
+                continue;
+            float volume_to_wipe = use_flush_matrix ?
+                wipe_volumes[current_extruder_id][extruder_id] * flush_multiplier :
+                (float) m_config.prime_volume;
+            float leftover = layer_tools.wiping_extrusions().mark_wiping_extrusions(*this, current_extruder_id, extruder_id,
+                                                                                    volume_to_wipe);
+            layer_leftover += leftover;
+            current_extruder_id = extruder_id;
+        }
+
+        // Plastic saving: drop the prism's fills that no toolchange on this layer
+        // claimed. At this point the prism's OVERRIDDEN fills are exactly the
+        // purge; the rest would print as solid infill in the prism's own filament
+        // for nothing -- which is the whole prism on a layer with no toolchange
+        // (141 of 692 layers on MCTEST5 before the truncation fix). Perimeters are
+        // left alone so the bar keeps a continuous wall along the belt.
+        //
+        // Non-destructive: the entities are stashed with their positions and put
+        // back by belt_restore_dropped_fills() at the top of the next plan. An
+        // earlier version deleted them outright, which broke replanning when a
+        // later tool ordering needed what this one had not claimed -- that is why
+        // it was removed rather than kept.
+        if (prism_po != nullptr) {
+            const auto &we = layer_tools.wiping_extrusions();
+            prism_po->belt_drop_unclaimed_fills(
+                prism_po->get_layer_at_printz(layer_tools.print_z, EPSILON),
+                [&we, prism_po](const ExtrusionEntity *e) { return we.is_entity_overridden(e, prism_po, 0); });
+        }
+
+        layer_tools.wiping_extrusions().ensure_perimeters_infills_order(*this);
+        if (layer_leftover > 0.f) {
+            total_leftover += layer_leftover;
+            if (layer_leftover > worst_layer_leftover) {
+                worst_layer_leftover = layer_leftover;
+                worst_layer_z        = layer_tools.print_z;
+            }
+        }
+        this->throw_if_canceled();
+    }
+
+    if (total_leftover > 1.f) {
+        this->active_step_add_warning(
+            PrintStateBase::WarningLevel::CRITICAL,
+            Slic3r::format(_u8L("The belt purge tower cannot absorb the full purge volume: %1% mm³ in total could not "
+                                "be purged (worst layer: %2% mm³ at height %3%). The print may show color bleeding. "
+                                "Increase the belt purge tower width, or reduce flushing volumes."),
+                           int(std::ceil(total_leftover)), int(std::ceil(worst_layer_leftover)),
+                           Slic3r::float_to_string_decimal_point(worst_layer_z, 2)));
+    }
+}
+
+// Belt mode: shift the sliced layer grid by delta. Mirrors the global_z_offset
+// application in slice() — layer print_z and belt_floor_z_shift move together
+// so belt floor clipping stays consistent with the shifted grid. Used by
+// Print::_align_belt_purge_layers() to snap the purge prism onto the printed
+// objects' layer grid; |delta| <= half a layer height, i.e. a sub-layer shift
+// of the prism along the belt.
+void PrintObject::belt_shift_layer_grid(double delta)
+{
+    if (std::abs(delta) < EPSILON)
+        return;
+    for (Layer *layer : m_layers)
+        layer->print_z += delta;
+    for (SupportLayer *layer : m_support_layers)
+        layer->print_z += delta;
+    // The brim's apron bands below the first layer carry their own print_z.
+    for (BeltBrimBand &band : m_belt_brim_prologue)
+        band.print_z += delta;
+    m_slicing_params.belt_floor_z_shift += delta;
+}
+
+// Belt mode: drop layers strictly above z (used to cancel the purge prism early
+// once there are no more toolchanges above z, so the tower stops at the last
+// color swap instead of wasting filament up the rest of the belt). Each layer's
+// cross-section is already sliced, so removing upper layers does not affect the
+// last toolchange's coverage. Deletes the Layer objects and clears the new top
+// layer's upper-layer link. Returns the number of layers removed.
+size_t PrintObject::belt_truncate_layers_above(coordf_t z)
+{
+    // A repeated plan always starts from the restored full layer set.
+    assert(m_belt_truncated_layers.empty());
+    size_t keep = m_layers.size();
+    while (keep > 0 && m_layers[keep - 1]->print_z > z + EPSILON)
+        --keep;
+    if (keep >= m_layers.size())
+        return 0;
+    const size_t removed = m_layers.size() - keep;
+    m_belt_truncated_layers.assign(m_layers.begin() + keep, m_layers.end());
+    m_layers.resize(keep);
+    if (!m_layers.empty())
+        m_layers.back()->upper_layer = nullptr;
+    return removed;
+}
+
+// Plastic saving on the purge prism: keep only the fills a toolchange claimed.
+//
+// Called per layer from _plan_belt_purge(), after the real-purge marking and
+// BEFORE ensure_perimeters_infills_order() -- that pass force-overrides every
+// remaining fill on the prism (it is a dedicated flush object), so afterwards
+// everything looks claimed and nothing could be distinguished.
+size_t PrintObject::belt_drop_unclaimed_fills(Layer *layer, const std::function<bool(const ExtrusionEntity*)> &claimed)
+{
+    if (layer == nullptr)
+        return 0;
+    size_t dropped = 0;
+    for (size_t ri = 0; ri < layer->regions().size(); ++ri) {
+        LayerRegion *lr = layer->get_region(ri);
+        auto        &ents = lr->fills.entities;
+        ExtrusionEntitiesPtr keep;
+        keep.reserve(ents.size());
+        for (size_t i = 0; i < ents.size(); ++i) {
+            if (claimed(ents[i])) {
+                keep.emplace_back(ents[i]);
+            } else {
+                // Stash with its original index so the restore is exact.
+                m_belt_dropped_fills.push_back(BeltDroppedFill{ layer, ri, i, ents[i] });
+                ++dropped;
+            }
+        }
+        ents = std::move(keep);
+    }
+    return dropped;
+}
+
+void PrintObject::belt_restore_dropped_fills()
+{
+    if (m_belt_dropped_fills.empty())
+        return;
+    // Ascending index per (layer, region): inserting in that order lands every
+    // entity back at its original position, because each insertion shifts only
+    // the entries after it, which are themselves still to be inserted.
+    std::stable_sort(m_belt_dropped_fills.begin(), m_belt_dropped_fills.end(),
+                     [](const BeltDroppedFill &a, const BeltDroppedFill &b) {
+                         if (a.layer != b.layer)           return a.layer < b.layer;
+                         if (a.region_idx != b.region_idx) return a.region_idx < b.region_idx;
+                         return a.index < b.index;
+                     });
+    for (const BeltDroppedFill &d : m_belt_dropped_fills) {
+        auto &ents = d.layer->get_region(d.region_idx)->fills.entities;
+        ents.insert(ents.begin() + std::min(d.index, ents.size()), d.entity);
+    }
+    m_belt_dropped_fills.clear();
+}
+
+void PrintObject::belt_restore_truncated_layers()
+{
+    if (m_belt_truncated_layers.empty())
+        return;
+
+    m_layers.insert(m_layers.end(), m_belt_truncated_layers.begin(), m_belt_truncated_layers.end());
+    m_belt_truncated_layers.clear();
+    for (size_t i = 0; i < m_layers.size(); ++i) {
+        m_layers[i]->lower_layer = i == 0 ? nullptr : m_layers[i - 1];
+        m_layers[i]->upper_layer = i + 1 < m_layers.size() ? m_layers[i + 1] : nullptr;
+    }
+}
+
+} // namespace Slic3r
@@ -0,0 +1,66 @@
+#include "BeltSliceStrategy.hpp"
+#include "Model.hpp"
+
+#include <limits>
+
+namespace Slic3r {
+
+void BeltSliceStrategy::apply_preslice_transforms(Transform3d           &trafo,
+                                                  const PrintConfig     &config,
+                                                  const ModelVolumePtrs &model_volumes,
+                                                  double                *out_belt_min_z)
+{
+    // 1. Standalone pre-slice axis remap (works without belt mode).
+    const bool has_remap = BeltTransformPipeline::has_preslice_remap(config);
+    if (has_remap)
+        trafo = BeltTransformPipeline::build_preslice_remap(config) * trafo;
+
+    // 2. Belt rotation — the sole mesh-side belt transform (matching
+    //    BeltTransformPipeline::build_forward_transform).  Only active in
+    //    belt-printer mode.
+    bool has_rotation = false;
+    if (config.belt_printer.value) {
+        const Matrix3d rot = BeltTransformPipeline::build_rotation_matrix(config, &has_rotation);
+        if (has_rotation) {
+            Transform3d belt_xform = Transform3d::Identity();
+            belt_xform.linear() = rot;
+            trafo = belt_xform * trafo;
+        }
+    }
+
+    if (!has_remap && !has_rotation)
+        return;
+
+    // 3. Z-shift — detect if the mesh clips below the build plate after the
+    // transforms and lift it.  Each mesh vertex must be brought into object space
+    // via mv->get_matrix() before applying the full trafo (which is in object
+    // space).  Missing this on assemblies (where per-volume get_matrix() positions
+    // each volume within the object) would compute min_z against mesh-local vertex
+    // coordinates rather than object-space coordinates, so volumes translated along
+    // the slicer's Z axis would be silently excluded from the bound check.
+
+    double min_z = std::numeric_limits<double>::max();
+    for (const ModelVolume *mv : model_volumes) {
+        if (!mv->is_model_part()) continue;
+        Transform3d vol_trafo = trafo * mv->get_matrix();
+        const auto &its = mv->mesh().its;
+        for (const stl_vertex &v : its.vertices) {
+            Vec3d vm = v.cast<double>();
+            Vec3d pt = vol_trafo * vm;
+            min_z = std::min(min_z, pt.z());
+        }
+    }
+    const double z_shift_val = (min_z < 0. && min_z != std::numeric_limits<double>::max()) ? -min_z : 0.;
+    if (z_shift_val > 0.) {
+        Transform3d z_shift = Transform3d::Identity();
+        z_shift.matrix()(2, 3) = z_shift_val;
+        trafo = z_shift * trafo;
+    }
+    // out_belt_min_z is only meaningful in belt mode; the standalone-remap path
+    // never reported it.
+    if (out_belt_min_z && config.belt_printer.value) {
+        *out_belt_min_z = (min_z != std::numeric_limits<double>::max()) ? min_z : 0.;
+    }
+}
+
+} // namespace Slic3r
@@ -0,0 +1,36 @@
+#pragma once
+
+#include "libslic3r.h"
+#include "Point.hpp"
+#include "BeltTransform.hpp"
+#include "PrintConfig.hpp"
+#include "Model.hpp"
+
+namespace Slic3r {
+
+// Belt printer / pre-slice transform strategy.
+//
+// Composes, in order, the pre-slice mesh transforms applied before slicing:
+//   1. Pre-slice axis remap (standalone — works without belt mode)
+//   2. Belt rotation (the sole mesh-side belt transform; shear & scale are a
+//      g-code-side stage, see MachineFrameTransform)
+//   3. Per-object Z-shift that lifts the mesh above the build plate
+//
+// Isolates this belt/remap-specific logic from the generic slicing pipeline in
+// PrintObjectSlice.cpp.
+class BeltSliceStrategy
+{
+public:
+    // Apply the pre-slice remap + belt rotation + Z-shift to `trafo` in place.
+    // No-op when neither a remap nor a belt rotation is configured.
+    //
+    // out_belt_min_z (if non-null) receives the minimum mesh Z after the
+    // transforms, but only in belt-printer mode — the standalone-remap path
+    // never reported it.
+    static void apply_preslice_transforms(Transform3d           &trafo,
+                                          const PrintConfig     &config,
+                                          const ModelVolumePtrs &model_volumes,
+                                          double                *out_belt_min_z = nullptr);
+};
+
+} // namespace Slic3r
@@ -0,0 +1,223 @@
+#include "BeltTransform.hpp"
+#include "Model.hpp"
+
+#include <limits>
+
+namespace Slic3r {
+
+// ---- Matrix builders ------------------------------------------------------
+
+Transform3d BeltTransformPipeline::build_preslice_remap(const PrintConfig &config)
+{
+    Transform3d pre_remap = Transform3d::Identity();
+    if (!has_preslice_remap(config))
+        return pre_remap;
+
+    int pre_rx = int(config.preslice_remap_x.value);
+    int pre_ry = int(config.preslice_remap_y.value);
+    int pre_rz = int(config.preslice_remap_z.value);
+
+    // Each remap value selects a source axis and sign.
+    auto remap_column = [](int r) -> Vec3d {
+        int axis = r % 3;
+        Vec3d col = Vec3d::Zero();
+        if (r < 3)      col[axis] =  1.0;  // +axis
+        else if (r < 6) col[axis] = -1.0;  // -axis
+        else            col[axis] = -1.0;  // Rev: max - pos = -(pos - max)
+        return col;
+    };
+
+    Matrix3d remap_lin;
+    remap_lin.col(0) = remap_column(pre_rx);
+    remap_lin.col(1) = remap_column(pre_ry);
+    remap_lin.col(2) = remap_column(pre_rz);
+    pre_remap.linear() = remap_lin;
+
+    // Translation for Rev modes (needs build volume extents).
+    if (pre_rx >= 6 || pre_ry >= 6 || pre_rz >= 6) {
+        BoundingBoxf bbox_bed(config.printable_area.values);
+        Vec3d vol_max(bbox_bed.max.x(), bbox_bed.max.y(),
+                      config.printable_height.value);
+        Vec3d remap_trans = Vec3d::Zero();
+        auto add_rev = [&](int r, int out) {
+            if (r >= 6) remap_trans[out] = vol_max[r % 3];
+        };
+        add_rev(pre_rx, 0);
+        add_rev(pre_ry, 1);
+        add_rev(pre_rz, 2);
+        pre_remap.translation() = remap_trans;
+    }
+
+    return pre_remap;
+}
+
+Matrix3d BeltTransformPipeline::build_rotation_matrix(const PrintConfig &config, bool *has_rot_out)
+{
+    BeltRotationAxis axis = config.belt_slice_rotation.value;
+    double angle_deg = config.belt_slice_rotation_angle.value;
+    bool active = axis != BeltRotationAxis::None && std::abs(angle_deg) > EPSILON;
+    if (has_rot_out) *has_rot_out = active;
+    if (!active)
+        return Matrix3d::Identity();
+    double angle_rad = Geometry::deg2rad(angle_deg);
+    Vec3d unit_axis;
+    switch (axis) {
+    case BeltRotationAxis::X: unit_axis = Vec3d::UnitX(); break;
+    case BeltRotationAxis::Y: unit_axis = Vec3d::UnitY(); break;
+    case BeltRotationAxis::Z: unit_axis = Vec3d::UnitZ(); break;
+    default:                  return Matrix3d::Identity();
+    }
+    return Eigen::AngleAxisd(angle_rad, unit_axis).toRotationMatrix();
+}
+
+Transform3d BeltTransformPipeline::build_forward_transform(const PrintConfig &config)
+{
+    // Mesh-side belt transform: rotation applied after the pre-slice axis remap.
+    // (Shear & scale are a g-code-side stage, not part of the mesh transform.)
+    Transform3d pre_remap = build_preslice_remap(config);
+    Matrix3d    rot       = build_rotation_matrix(config);
+
+    Transform3d combined = Transform3d::Identity();
+    combined.linear() = rot;
+    combined = combined * pre_remap;
+    return combined;
+}
+
+// ---- Bounding box remap ---------------------------------------------------
+
+BoundingBoxf3 BeltTransformPipeline::remap_bbox(const BoundingBoxf3 &bb, const PrintConfig &config)
+{
+    int pre_rx = int(config.preslice_remap_x.value);
+    int pre_ry = int(config.preslice_remap_y.value);
+    int pre_rz = int(config.preslice_remap_z.value);
+
+    if (pre_rx == int(RemapAxis::PosX) &&
+        pre_ry == int(RemapAxis::PosY) &&
+        pre_rz == int(RemapAxis::PosZ))
+        return bb;  // Identity remap.
+
+    auto remap_coord = [](int r, const Vec3d &v) -> double {
+        int axis = r % 3;
+        if (r < 3) return v[axis];
+        return -v[axis];
+    };
+
+    Vec3d mn = bb.min.cast<double>(), mx = bb.max.cast<double>();
+    BoundingBoxf3 rbb;
+    for (int i = 0; i < 8; ++i) {
+        Vec3d c((i & 1) ? mx.x() : mn.x(),
+                (i & 2) ? mx.y() : mn.y(),
+                (i & 4) ? mx.z() : mn.z());
+        Vec3d rc(remap_coord(pre_rx, c), remap_coord(pre_ry, c), remap_coord(pre_rz, c));
+        if (i == 0) rbb = BoundingBoxf3(rc, rc);
+        else rbb.merge(rc);
+    }
+    return rbb;
+}
+
+BoundingBoxf3 BeltTransformPipeline::remap_bbox(const ModelObject &model_object, const PrintConfig &config)
+{
+    return remap_bbox(model_object.raw_bounding_box(), config);
+}
+
+// ---- Belt floor parameters ------------------------------------------------
+
+// Shared implementation for both PrintConfig and DynamicPrintConfig.
+// Template avoids duplicating the math for the two config types.
+namespace {
+
+template<typename Config>
+BeltTransformPipeline::BeltHeightResult compute_belt_height_and_floor_impl(
+    const Config &config, const BoundingBoxf3 &bb, double original_height)
+{
+    BeltTransformPipeline::BeltHeightResult result;
+    result.object_height = original_height;
+
+    // Extract the mesh rotation from config (the sole mesh-side belt transform).
+    BeltRotationAxis rot_axis;
+    double           rot_angle;
+
+    if constexpr (std::is_same_v<Config, PrintConfig>) {
+        rot_axis  = config.belt_slice_rotation.value;
+        rot_angle = config.belt_slice_rotation_angle.value;
+    } else {
+        // DynamicPrintConfig path
+        auto get_float = [&](const char *key) {
+            auto *opt = config.template option<ConfigOptionFloat>(key);
+            return opt ? opt->value : 0.0;
+        };
+        auto get_rot_axis = [&](const char *key) {
+            auto *opt = config.template option<ConfigOptionEnum<BeltRotationAxis>>(key);
+            return opt ? opt->value : BeltRotationAxis::None;
+        };
+        rot_axis  = get_rot_axis("belt_slice_rotation");
+        rot_angle = get_float("belt_slice_rotation_angle");
+    }
+
+    bool has_rotation = rot_axis != BeltRotationAxis::None && std::abs(rot_angle) > EPSILON;
+    if (!has_rotation)
+        return result;
+
+    // Rotation path: sweep the 8 bbox corners through R to get the rotated height,
+    // then derive the belt floor (the image of machine-Z = 0 under R).
+    double angle_rad = Geometry::deg2rad(rot_angle);
+    Vec3d unit_axis;
+    switch (rot_axis) {
+    case BeltRotationAxis::X: unit_axis = Vec3d::UnitX(); break;
+    case BeltRotationAxis::Y: unit_axis = Vec3d::UnitY(); break;
+    case BeltRotationAxis::Z: unit_axis = Vec3d::UnitZ(); break;
+    default:                  unit_axis = Vec3d::UnitX(); break;
+    }
+    Matrix3d R = Eigen::AngleAxisd(angle_rad, unit_axis).toRotationMatrix();
+    double min_rz = std::numeric_limits<double>::max();
+    double max_rz = std::numeric_limits<double>::lowest();
+    for (int i = 0; i < 8; ++i) {
+        Vec3d c((i & 1) ? bb.max.x() : bb.min.x(),
+                (i & 2) ? bb.max.y() : bb.min.y(),
+                (i & 4) ? bb.max.z() : bb.min.z());
+        double z = (R * c).z();
+        min_rz = std::min(min_rz, z);
+        max_rz = std::max(max_rz, z);
+    }
+    result.object_height = max_rz - min_rz;
+
+    // Belt floor in slicer-frame is the image of z_machine = 0 under R.
+    //   R(+α, X): point (·, y, 0) → (·, cos α · y, sin α · y) ⇒ z = tan(α) · y_s
+    //   R(+α, Y): point (x, ·, 0) → (cos α · x, ·, -sin α · x) ⇒ z = -tan(α) · x_s
+    //   R(+α, Z): point (·, ·, 0) → (·, ·, 0); no tilt → no floor
+    double sin_a = std::sin(angle_rad), cos_a = std::cos(angle_rad);
+    switch (rot_axis) {
+    case BeltRotationAxis::X:
+        result.floor_params.shear_factor = (std::abs(cos_a) > EPSILON) ?  sin_a / cos_a : 0.;
+        result.floor_params.from_axis    = 1; // Y
+        break;
+    case BeltRotationAxis::Y:
+        result.floor_params.shear_factor = (std::abs(cos_a) > EPSILON) ? -sin_a / cos_a : 0.;
+        result.floor_params.from_axis    = 0; // X
+        break;
+    case BeltRotationAxis::Z:
+    default:
+        result.floor_params.shear_factor = 0.0;
+        result.floor_params.from_axis    = 1;
+        break;
+    }
+    result.floor_params.z_shift = bb.min.z() + ((min_rz < 0.) ? -min_rz : 0.);
+
+    return result;
+}
+
+} // anonymous namespace
+
+BeltTransformPipeline::BeltHeightResult BeltTransformPipeline::compute_belt_height_and_floor(
+    const PrintConfig &config, const BoundingBoxf3 &remapped_bbox, double original_height)
+{
+    return compute_belt_height_and_floor_impl(config, remapped_bbox, original_height);
+}
+
+BeltTransformPipeline::BeltHeightResult BeltTransformPipeline::compute_belt_height_and_floor(
+    const DynamicPrintConfig &config, const BoundingBoxf3 &remapped_bbox, double original_height)
+{
+    return compute_belt_height_and_floor_impl(config, remapped_bbox, original_height);
+}
+
+} // namespace Slic3r
@@ -0,0 +1,152 @@
+#pragma once
+
+#include "libslic3r.h"
+#include "Point.hpp"
+#include "BoundingBox.hpp"
+#include "PrintConfig.hpp"
+#include "Geometry.hpp"
+
+#include <cmath>
+
+namespace Slic3r {
+
+class ModelObject;
+
+// Shared belt-printer transform math.
+//
+// The pre-slice pipeline applied in PrintObjectSlice.cpp is:
+//     trafo_out = z_shift * rotation * pre_remap * trafo_in
+//
+// Rotation is the sole mesh-side belt transform; shear & scale are applied
+// to the g-code instead (see MachineFrameTransform).  This class provides the
+// building blocks so every call site uses the same implementation.  z_shift is
+// object-dependent (computed from mesh vertex bounds) and is NOT included in
+// build_forward_transform().  The machine-frame shear/scale is derived directly
+// from the tilt angle in MachineFrameTransform and no longer lives here.
+//
+// Design note: this mesh-rotation approach replaced an earlier pre-shear
+// method (now removed).  While that initial pre-shear method was instrumental
+// in getting belt printer slicing off the ground in the first place, its place is
+// in the past.  A big thank you goes to the Unlayered3D team, who recommended 
+// switching to a pre-slice rotation stage instead.  Doing so keeps the slicing 
+// operation isometric — no distortion of the sliced geometry — while the 
+// non-orthogonal machine-axis compensation is confined to a g-code-side shear/scale
+// derived from the same tilt angle.
+// 
+// This fixed a number of issues, including several issues noticed by hotcubcar
+// regarding adaptive infills not working, gyroid becoming anisotropic, and more 
+// that were all mostly resolved as a result of the switch.
+// 
+// This also means that the pre-slice rotation transform methodology can be used 
+// more cleanly on non-belt printers.
+// - HarrierPigeon (Joseph Robertson)
+
+class BeltTransformPipeline
+{
+public:
+    // ---- Identity checks --------------------------------------------------
+
+    static bool has_preslice_remap(const PrintConfig &config)
+    {
+        return int(config.preslice_remap_x.value) != int(RemapAxis::PosX) ||
+               int(config.preslice_remap_y.value) != int(RemapAxis::PosY) ||
+               int(config.preslice_remap_z.value) != int(RemapAxis::PosZ);
+    }
+
+    // Overload accepting DynamicPrintConfig (used in static slicing_parameters).
+    static bool has_preslice_remap(const DynamicPrintConfig &config)
+    {
+        auto get_int = [&](const char *key) -> int {
+            auto *opt = config.option<ConfigOptionEnum<RemapAxis>>(key);
+            return opt ? int(opt->value) : 0;
+        };
+        return get_int("preslice_remap_x") != int(RemapAxis::PosX) ||
+               get_int("preslice_remap_y") != int(RemapAxis::PosY) ||
+               get_int("preslice_remap_z") != int(RemapAxis::PosZ);
+    }
+
+    static bool has_rotation(const PrintConfig &config)
+    {
+        return config.belt_slice_rotation.value != BeltRotationAxis::None &&
+               std::abs(config.belt_slice_rotation_angle.value) > EPSILON;
+    }
+
+    // Physical belt tilt derived from the slicing rotation — the single source of
+    // truth for bed rendering, support gravity tilt and the bed-exclusion
+    // projection.  Returns the tilt magnitude in degrees split onto the X and Y
+    // build-plate tilt axes according to the rotation axis:
+    //   rotation about X  → tilt_x = angle   (gantry tilts in the YZ plane)
+    //   rotation about Y  → tilt_y = angle   (gantry tilts in the XZ plane)
+    //   rotation about Z / None → no tilt    (in-plane spin doesn't tilt the belt)
+    // The magnitude uses abs(angle) so a negative rotation still reports a positive
+    // physical tilt.
+    struct PhysicalTilt { double tilt_x_deg = 0.; double tilt_y_deg = 0.; };
+
+    static PhysicalTilt physical_tilt(BeltRotationAxis axis, double angle_deg)
+    {
+        PhysicalTilt t;
+        double mag = std::abs(angle_deg);
+        switch (axis) {
+        case BeltRotationAxis::X: t.tilt_x_deg = mag; break;
+        case BeltRotationAxis::Y: t.tilt_y_deg = mag; break;
+        default: break; // Z / None: no physical tilt
+        }
+        return t;
+    }
+
+    static PhysicalTilt physical_tilt(const PrintConfig &config)
+    {
+        return physical_tilt(config.belt_slice_rotation.value,
+                             config.belt_slice_rotation_angle.value);
+    }
+
+    // ---- Matrix builders --------------------------------------------------
+
+    // Build the pre-slice axis remap transform (includes Rev-mode translation).
+    static Transform3d build_preslice_remap(const PrintConfig &config);
+
+    // Build the 3x3 rotation matrix from belt_slice_rotation* config.
+    // Returns Identity if rotation axis is None or angle is ~0.
+    // Also sets has_rot_out if non-null.
+    static Matrix3d build_rotation_matrix(const PrintConfig &config, bool *has_rot_out = nullptr);
+
+    // Combined forward transform (rotation * pre_remap) — the mesh-side belt
+    // transform that BeltSliceStrategy applies and BeltBackTransform inverts.
+    // Does NOT include the per-object Z-shift.
+    static Transform3d build_forward_transform(const PrintConfig &config);
+
+    // ---- Bounding box remap -----------------------------------------------
+
+    // Remap a bounding box through the pre-slice axis remap.
+    // Returns the original bbox if remap is identity.
+    static BoundingBoxf3 remap_bbox(const BoundingBoxf3 &bb, const PrintConfig &config);
+    static BoundingBoxf3 remap_bbox(const ModelObject &model_object, const PrintConfig &config);
+
+    // ---- Belt floor parameters --------------------------------------------
+
+    struct BeltFloorParams {
+        double shear_factor = 0.0;
+        int    from_axis    = 1;
+        double z_shift      = 0.0;
+    };
+
+    // Result of computing belt height + floor params.
+    struct BeltHeightResult {
+        double          object_height;  // Effective object height after shear/scale
+        BeltFloorParams floor_params;
+    };
+
+    // Compute effective object height and belt floor parameters from config
+    // and pre-remapped bounding box.  original_height is the input height
+    // (bb.size().z() or model_object.max_z()).
+    static BeltHeightResult compute_belt_height_and_floor(
+        const PrintConfig &config, const BoundingBoxf3 &remapped_bbox,
+        double original_height);
+
+    // Overload for DynamicPrintConfig (used by static slicing_parameters).
+    static BeltHeightResult compute_belt_height_and_floor(
+        const DynamicPrintConfig &config, const BoundingBoxf3 &remapped_bbox,
+        double original_height);
+};
+
+} // namespace Slic3r
@@ -449,7 +449,9 @@ static ExPolygons outer_inner_brim_area(const Print& print,
            const bool         use_brim_ears = object->config().brim_type == btPainted;
            const bool         use_inner_brim_ears = (use_auto_brim_ears || use_brim_ears) && !object->config().brim_ears_outer_only.value;
            const bool         has_inner_brim = brim_type == btInnerOnly || brim_type == btOuterAndInner || use_inner_brim_ears;
-            const bool         has_outer_brim = brim_type == btOuterOnly || brim_type == btOuterAndInner || brim_type == btAutoBrim || use_auto_brim_ears || use_brim_ears;
+            // btLeadingEdgeOnly is a belt-printer mode; on a flat bed there is no leading
+            // edge, so it degrades to an ordinary outer brim rather than silently to none.
+            const bool         has_outer_brim = brim_type == btOuterOnly || brim_type == btOuterAndInner || brim_type == btAutoBrim || brim_type == btLeadingEdgeOnly || use_auto_brim_ears || use_brim_ears;
            coord_t            ear_detection_length = scale_(object->config().brim_ears_detection_length.value);
            coordf_t           brim_ears_max_angle = object->config().brim_ears_max_angle.value;
            //ORCA: Select brim base slices from EFC-compensated outline when enabled.
@@ -864,6 +866,17 @@ void make_brim(const Print& print, PrintTryCancel try_cancel, Polygons& islands_
    std::vector<unsigned int>& printExtruders,
    std::map<ObjectInstanceID, ExPolygons>* objectBrimAreasByInstanceOut)
 {
+    // Belt printers never use the flat plate brim.
+    //
+    // With a tilted belt the brim has to be laid onto the belt plane over many layers,
+    // which BeltBrim.cpp does during posSupportMaterial.  With an untilted belt this
+    // could in principle fall through and produce an ordinary brim, but it would never
+    // reach the G-code: the plate brim is emitted out of skirt_brim_groups(), which
+    // _make_skirt() builds, and that returns early for every belt printer.  Running the
+    // generator anyway would just burn time on geometry nobody prints.
+    if (print.config().belt_printer.value)
+        return;
+
    std::map<ObjectInstanceID, ExPolygons> brimAreaMap;
    Flow                 flow = print.brim_flow();
    ExPolygons           islands_area_ex = outer_inner_brim_area(print,
@@ -80,7 +80,7 @@ public:
    indexed_triangle_set        bounding_mesh(bool scale=true) const;

    // Center of the print bed, unscaled.
-    Vec2d                       bed_center()        const { return to_2d(m_bboxf.center()); }
+    Vec2d                       bed_center()        const { return get_extents(m_bed_shape).center(); }
    // Convex hull of polygon(), scaled.
    const Polygon&              convex_hull()       const { return m_convex_hull; }
    // Smallest enclosing circle of polygon(), scaled.
@@ -80,6 +80,17 @@ set(lisbslic3r_sources
    BoundingBox.hpp
    BridgeDetector.cpp
    BridgeDetector.hpp
+    BeltBrim.cpp
+    BeltBrim.hpp
+    BeltGCode.cpp
+    BeltGCode.hpp
+    BeltPurge.cpp
+    BeltSliceStrategy.cpp
+    BeltSliceStrategy.hpp
+    BeltTransform.cpp
+    BeltTransform.hpp
+    FirstLayerPlane.cpp
+    FirstLayerPlane.hpp
    Brim.cpp
    BrimEarsPoint.hpp
    Brim.hpp
@@ -228,6 +239,14 @@ set(lisbslic3r_sources
    GCode/AdaptivePAProcessor.hpp
    GCode/AvoidCrossingPerimeters.cpp
    GCode/AvoidCrossingPerimeters.hpp
+    GCode/BeltBackTransform.cpp
+    GCode/BeltBackTransform.hpp
+    GCode/MachineFrameTransform.cpp
+    GCode/MachineFrameTransform.hpp
+    GCode/BeltKinematics.cpp
+    GCode/BeltKinematics.hpp
+    GCode/MachineKinematics.cpp
+    GCode/MachineKinematics.hpp
    GCode/ConflictChecker.cpp
    GCode/ConflictChecker.hpp
    GCode/CoolingBuffer.cpp
@@ -442,6 +461,8 @@ set(lisbslic3r_sources
    SlicingAdaptive.hpp
    Slicing.cpp
    Slicing.hpp
+    Support/BeltFloorContext.cpp
+    Support/BeltFloorContext.hpp
    Support/SupportCommon.cpp
    Support/SupportCommon.hpp
    Support/SupportLayer.hpp
@@ -396,6 +396,11 @@ inline void translate(ExPolygons &expolys, const Point &p) {
        expoly.translate(p);
 }

+inline void translate(Polygons &polys, const Point &p) {
+    for (Polygon &poly : polys)
+        poly.translate(p);
+}
+
 inline void polygons_append(Polygons &dst, const ExPolygon &src) 
 { 
    dst.reserve(dst.size() + src.holes.size() + 1);
@@ -0,0 +1,225 @@
+#include "FirstLayerPlane.hpp"
+#include "BeltTransform.hpp"
+
+#include <algorithm>
+#include <climits>
+#include <cmath>
+
+namespace Slic3r {
+
+namespace {
+
+// Build the row of the gcode-axis-remap matrix R that produces machine_Z,
+// AS A FUNCTION OF a slicing-frame point in the GCode generator's coordinate
+// space.  Without back-transform this is just R.row(2).  With back-transform
+// the writer applies F^-1 before R, so the effective row is (R * F^-1).row(2).
+//
+// Returns a pair (gradient, constant) such that:
+//     machine_Z(p_slicing) = gradient.dot(p_slicing) + constant
+struct MachineZAffine {
+    Vec3d  gradient = Vec3d::UnitZ();
+    double constant = 0.0;
+};
+
+MachineZAffine compute_machine_z_affine(const PrintConfig &config)
+{
+    MachineZAffine out;
+
+    // R is the matrix form of GCodeWriter::apply_axis_remap.  Each output axis
+    // i picks one slicing-frame component (with sign + optional Rev mode
+    // translation) based on m_remap_{x,y,z}.  We only need row 2 (the z output)
+    // since machine_Z is what defines the first-layer plane.
+    int rz = int(config.gcode_remap_z.value);
+    int axis = rz % 3;
+    double sign;
+    double trans;
+    if (rz < int(RemapAxis::NegX)) {            // 0..2 = PosX/Y/Z
+        sign  = 1.0;
+        trans = 0.0;
+    } else if (rz < int(RemapAxis::RevX)) {     // 3..5 = NegX/Y/Z
+        sign  = -1.0;
+        trans = 0.0;
+    } else {                                     // 6..8 = RevX/Y/Z
+        sign = -1.0;
+        BoundingBoxf bbox_bed(config.printable_area.values);
+        Vec3d vol_max(bbox_bed.max.x(),
+                      bbox_bed.max.y(),
+                      config.printable_height.value);
+        trans = vol_max[axis];
+    }
+
+    Vec3d r_row = Vec3d::Zero();
+    r_row[axis] = sign;
+
+    // Without back-transform, machine_Z(slicing) = r_row · slicing + trans.
+    out.gradient = r_row;
+    out.constant = trans;
+
+    if (config.gcode_back_transform.value && config.belt_printer.value) {
+        // BeltKinematics applies F^-1 before R when back-transform is on.
+        // So machine_Z(slicing) = r_row · (F^-1 · slicing) + trans
+        //                       = (r_row^T · F^-1) · slicing + trans
+        // We need to compose r_row with F^-1 from the LEFT (treating r_row as
+        // a row vector).  Eigen makes this easy: it's just F^-1.transpose() * r_row.
+        Transform3d forward = BeltTransformPipeline::build_forward_transform(config);
+        Transform3d inverse = forward.inverse();
+        // Note: forward.translation() is normally zero (per-print transforms
+        // don't add a translation; the per-object z_shift is added separately
+        // in PrintObjectSlice).  We still incorporate inverse.translation() in
+        // case a Rev-mode preslice_remap puts a translation in F.
+        Vec3d composed_grad = inverse.linear().transpose() * r_row;
+        double composed_trans =
+            r_row.dot(inverse.translation()) + trans;
+        out.gradient = composed_grad;
+        out.constant = composed_trans;
+    }
+
+    return out;
+}
+
+} // namespace
+
+FirstLayerPlane::FirstLayerPlane(const PrintConfig &config)
+{
+    // -------- Resolve Auto -------------------------------------------------
+    FirstLayerPlaneMode mode = config.first_layer_plane.value;
+    if (mode == FirstLayerPlaneMode::Auto) {
+        bool belt_affine_active = config.belt_printer.value &&
+            config.belt_slice_rotation.value != BeltRotationAxis::None &&
+            std::abs(config.belt_slice_rotation_angle.value) > EPSILON;
+        mode = belt_affine_active ? FirstLayerPlaneMode::BeltAffine
+                                  : FirstLayerPlaneMode::XY;
+    }
+    m_mode = mode;
+
+    // -------- Band thickness ----------------------------------------------
+    // Note: layer_height lives in PrintObjectConfig, not PrintConfig, so we
+    // can't fall back to it from here.  initial_layer_print_height is in
+    // PrintConfig and is the right default anyway (the legacy first-layer
+    // semantics used initial_layer_print_height, not the regular one).
+    double thickness = config.first_layer_plane_thickness.value;
+    if (thickness <= 0.0)
+        thickness = config.initial_layer_print_height.value;
+    if (thickness <= 0.0)
+        thickness = 0.2;
+    m_thickness_mm = thickness;
+
+    const double user_offset = config.first_layer_plane_offset.value;
+
+    // -------- Build the plane ---------------------------------------------
+    auto set_axis_aligned = [&](const Vec3d &n_unit, double offset_along_n) {
+        m_normal = n_unit;
+        m_offset = offset_along_n;
+    };
+
+    switch (mode) {
+    case FirstLayerPlaneMode::XY:
+        // Legacy XY plane.  Inactive: short-circuit to layer-index path.
+        set_axis_aligned(Vec3d::UnitZ(), user_offset);
+        m_active = false;
+        return;
+
+    case FirstLayerPlaneMode::YZ:
+        set_axis_aligned(Vec3d::UnitX(), user_offset);
+        m_active = true;
+        return;
+
+    case FirstLayerPlaneMode::XZ:
+        set_axis_aligned(Vec3d::UnitY(), user_offset);
+        m_active = true;
+        return;
+
+    case FirstLayerPlaneMode::BeltAffine: {
+        // Compute the slicing-frame plane that maps to machine_Z = user_offset
+        // under the gcode axis remap (and optional back-transform).
+        MachineZAffine mz = compute_machine_z_affine(config);
+        double cmag = mz.gradient.norm();
+        if (cmag < EPSILON) {
+            // Degenerate: slicing point doesn't affect machine_Z.  Fall back.
+            set_axis_aligned(Vec3d::UnitZ(), user_offset);
+            m_active = false;
+            return;
+        }
+        // Plane equation: gradient · slicing = user_offset - constant
+        const double K = user_offset - mz.constant;
+        m_normal = mz.gradient / cmag;
+        m_offset = K / cmag;
+        m_active = true;
+        return;
+    }
+
+    case FirstLayerPlaneMode::Auto:
+        // Should have been resolved above.
+        m_active = false;
+        return;
+    }
+
+    m_active = false;
+}
+
+double FirstLayerPlane::distance_from_plane(const Vec3d &point_slicing_mm) const
+{
+    return m_normal.dot(point_slicing_mm) - m_offset;
+}
+
+bool FirstLayerPlane::is_first_layer(const Vec3d &point_slicing_mm,
+                                     double first_layer_height_mm) const
+{
+    if (!m_active)
+        return false;
+    return distance_from_plane(point_slicing_mm) < first_layer_height_mm;
+}
+
+int FirstLayerPlane::effective_layer_index(const Vec3d &point_slicing_mm) const
+{
+    if (!m_active)
+        return INT_MAX / 2;  // Effectively "way past first layer".
+    double d = distance_from_plane(point_slicing_mm);
+    if (d <= 0.0)
+        return 0;
+    return int(std::floor(d / m_thickness_mm));
+}
+
+int FirstLayerPlane::min_effective_index_for_xy_bbox(
+    const BoundingBoxf &xy_bbox_mm, double slicing_z_mm) const
+{
+    if (!m_active)
+        return INT_MAX / 2;
+    // For the rectangular bbox in (x, y) at fixed z, the smallest value of
+    // (n.x*x + n.y*y + n.z*z - offset) is achieved at one of the four
+    // corners, with the smaller component picked when the corresponding
+    // normal coefficient is positive.
+    const double x_for_min = (m_normal.x() >= 0.0)
+        ? xy_bbox_mm.min.x() : xy_bbox_mm.max.x();
+    const double y_for_min = (m_normal.y() >= 0.0)
+        ? xy_bbox_mm.min.y() : xy_bbox_mm.max.y();
+    const double dmin = m_normal.x() * x_for_min
+                      + m_normal.y() * y_for_min
+                      + m_normal.z() * slicing_z_mm
+                      - m_offset;
+    if (dmin <= 0.0)
+        return 0;
+    return int(std::floor(dmin / m_thickness_mm));
+}
+
+int FirstLayerPlane::min_effective_index_for_bbox3(
+    const BoundingBoxf3 &bbox_mm) const
+{
+    if (!m_active)
+        return INT_MAX / 2;
+    const double x_for_min = (m_normal.x() >= 0.0)
+        ? bbox_mm.min.x() : bbox_mm.max.x();
+    const double y_for_min = (m_normal.y() >= 0.0)
+        ? bbox_mm.min.y() : bbox_mm.max.y();
+    const double z_for_min = (m_normal.z() >= 0.0)
+        ? bbox_mm.min.z() : bbox_mm.max.z();
+    const double dmin = m_normal.x() * x_for_min
+                      + m_normal.y() * y_for_min
+                      + m_normal.z() * z_for_min
+                      - m_offset;
+    if (dmin <= 0.0)
+        return 0;
+    return int(std::floor(dmin / m_thickness_mm));
+}
+
+} // namespace Slic3r
@@ -0,0 +1,76 @@
+#ifndef slic3r_FirstLayerPlane_hpp_
+#define slic3r_FirstLayerPlane_hpp_
+
+#include "libslic3r.h"
+#include "Point.hpp"
+#include "BoundingBox.hpp"
+#include "PrintConfig.hpp"
+
+namespace Slic3r {
+
+// Decides which extrusions get "first layer" treatment (no fan, slow speed,
+// initial-layer accel/jerk, deferred temperature drop) by reference to a
+// configurable plane in slicing-frame coordinates rather than the slicing
+// layer index.
+//
+// On a normal flat-bed printer the plane is XY at slicing_Z = 0 and the
+// evaluator is INACTIVE — every call site short-circuits back to the legacy
+// `Layer::id() == 0` test.  On a belt printer with a Z-from-Y shear the
+// belt surface (machine_Z = 0) maps to a plane in slicing-frame coordinates
+// derived from the gcode axis remap, so layer-index-based detection no
+// longer matches the physical first printed surface.
+//
+// Plane representation: unit normal `n` (slicing frame) and offset along
+// the normal such that the plane equation is `n · p == offset`.  Signed
+// perpendicular distance is `d(p) = n · p - offset`.  Positive distance
+// means "away from the belt surface", negative means "below the plane".
+class FirstLayerPlane
+{
+public:
+    explicit FirstLayerPlane(const PrintConfig &config);
+
+    // Inactive when the legacy XY layer-index path should be used.  This
+    // covers all non-belt printers and any belt printer where the user
+    // explicitly picked XY mode.
+    bool                is_active() const     { return m_active; }
+    FirstLayerPlaneMode effective_mode() const{ return m_mode; }
+    double              band_thickness_mm() const { return m_thickness_mm; }
+    const Vec3d &       normal() const        { return m_normal; }
+    double              plane_offset() const  { return m_offset; }
+
+    // Signed perpendicular distance from a slicing-frame point to the plane.
+    double distance_from_plane(const Vec3d &point_slicing_mm) const;
+
+    // True if perpendicular distance < first_layer_height_mm.  When the
+    // evaluator is inactive this returns false (call sites should fall back
+    // to the legacy per-layer path before reaching this function).
+    bool is_first_layer(const Vec3d &point_slicing_mm,
+                        double first_layer_height_mm) const;
+
+    // floor((distance - 0) / band_thickness), clamped to [0, +inf).  Used
+    // for "first N layers" thresholds (fan, slow_down_layers).  Returns 0
+    // for points within the band.  Returns INT_MAX/2 when inactive.
+    int effective_layer_index(const Vec3d &point_slicing_mm) const;
+
+    // Min effective index over a 2D bbox at a fixed slicing_Z.  Used for
+    // layer-level decisions (e.g. temperature transition gate) where we
+    // don't want to walk every extrusion in the layer.  For axis-aligned
+    // planes this is exact; for tilted planes it's a tight lower bound
+    // (the plane projection of the bbox's extreme corner).
+    int min_effective_index_for_xy_bbox(const BoundingBoxf &xy_bbox_mm,
+                                        double              slicing_z_mm) const;
+
+    // Same as above but the bbox spans a Z range too.
+    int min_effective_index_for_bbox3(const BoundingBoxf3 &bbox_mm) const;
+
+private:
+    bool                m_active        = false;
+    FirstLayerPlaneMode m_mode          = FirstLayerPlaneMode::XY;
+    Vec3d               m_normal        = Vec3d::UnitZ();  // unit, slicing frame
+    double              m_offset        = 0.0;             // n·p == m_offset
+    double              m_thickness_mm  = 0.0;
+};
+
+} // namespace Slic3r
+
+#endif // slic3r_FirstLayerPlane_hpp_
@@ -978,10 +978,10 @@ void PlateData::parse_filament_info(GCodeProcessorResult *result)
            void _stop_object_xml_parser(const std::string& msg = std::string())
            {
                assert(! obj_parse_error);
-                assert(obj_parse_error_message.empty());
                assert(object_xml_parser != nullptr);
                obj_parse_error = true;
-                obj_parse_error_message = msg;
+                if (! msg.empty() || obj_parse_error_message.empty())   // a handler may have set the message already
+                    obj_parse_error_message = msg;
                XML_StopParser(object_xml_parser, false);
            }

@@ -3815,11 +3815,18 @@ void PlateData::parse_filament_info(GCodeProcessorResult *result)
    {
        // appends the vertex coordinates
        // missing values are set equal to ZERO
-        if (m_curr_object)
-            m_curr_object->geometry.vertices.emplace_back(
-                m_unit_factor * bbs_get_attribute_value_float(attributes, num_attributes, X_ATTR),
-                m_unit_factor * bbs_get_attribute_value_float(attributes, num_attributes, Y_ATTR),
-                m_unit_factor * bbs_get_attribute_value_float(attributes, num_attributes, Z_ATTR));
+        if (m_curr_object) {
+            const Vec3f v(m_unit_factor * bbs_get_attribute_value_float(attributes, num_attributes, X_ATTR),
+                          m_unit_factor * bbs_get_attribute_value_float(attributes, num_attributes, Y_ATTR),
+                          m_unit_factor * bbs_get_attribute_value_float(attributes, num_attributes, Z_ATTR));
+            // A non-finite coordinate ("nan", "inf") used to be accepted and crashed
+            // qhull in ModelVolume's convex hull while the file was still loading. Refuse the file.
+            if (! v.allFinite()) {
+                _stop_xml_parser("Invalid vertex coordinate: not a finite number");
+                return true;   // the parser is stopped; returning false would overwrite the message
+            }
+            m_curr_object->geometry.vertices.emplace_back(v);
+        }
        return true;
    }

@@ -5109,6 +5116,11 @@ void PlateData::parse_filament_info(GCodeProcessorResult *result)
                    }
                }

+                for (const Vec3f &v : sub_object->geometry.vertices)
+                    if (! v.allFinite()) {   // Qhull cannot take a NaN vertex
+                        add_error("invalid (non-finite) vertex in object " + std::to_string(sub_object->id));
+                        return false;
+                    }
                its.vertices.assign(sub_object->geometry.vertices.begin(), sub_object->geometry.vertices.end());

                // BBS
@@ -5600,11 +5612,18 @@ void PlateData::parse_filament_info(GCodeProcessorResult *result)
    {
        // appends the vertex coordinates
        // missing values are set equal to ZERO
-        if (current_object)
-            current_object->geometry.vertices.emplace_back(
-                object_unit_factor * bbs_get_attribute_value_float(attributes, num_attributes, X_ATTR),
-                object_unit_factor * bbs_get_attribute_value_float(attributes, num_attributes, Y_ATTR),
-                object_unit_factor * bbs_get_attribute_value_float(attributes, num_attributes, Z_ATTR));
+        if (current_object) {
+            const Vec3f v(object_unit_factor * bbs_get_attribute_value_float(attributes, num_attributes, X_ATTR),
+                          object_unit_factor * bbs_get_attribute_value_float(attributes, num_attributes, Y_ATTR),
+                          object_unit_factor * bbs_get_attribute_value_float(attributes, num_attributes, Z_ATTR));
+            // See _BBS_3MF_Importer::_handle_start_vertex: a non-finite coordinate
+            // crashed qhull while the file loaded. The dispatcher stops this parser on `false`.
+            if (! v.allFinite()) {
+                obj_parse_error_message = "Invalid vertex coordinate: not a finite number";
+                return false;
+            }
+            current_object->geometry.vertices.emplace_back(v);
+        }
        return true;
    }

@@ -2,8 +2,11 @@
 #define slic3r_GCode_hpp_

 #include "libslic3r.h"
+#include <limits>
 #include "ExPolygon.hpp"
 #include "GCodeWriter.hpp"
+#include "GCode/BeltKinematics.hpp"
+#include "FirstLayerPlane.hpp"
 #include "Layer.hpp"
 #include "Point.hpp"
 #include "PlaceholderParser.hpp"
@@ -31,6 +34,7 @@

 #include <memory>
 #include <map>
+#include <optional>
 #include <set>
 #include <string>
 #include <cfloat>
@@ -214,16 +218,18 @@ public:
        m_last_obj_copy(nullptr, Point(std::numeric_limits<coord_t>::max(), std::numeric_limits<coord_t>::max())),
        // BBS
        m_toolchange_count(0),
-        m_nominal_z(0.)
+        m_nominal_z(0.),
+        m_writer(std::make_unique<GCodeWriter>())
        {}
-    ~GCode() = default;
+    virtual ~GCode() = default;

+public:
    // throws std::runtime_exception on error,
    // throws CanceledException through print->throw_if_canceled().
    void            do_export(Print* print, const char* path, GCodeProcessorResult* result = nullptr, ThumbnailsGeneratorCallback thumbnail_cb = nullptr);
    void            export_layer_filaments(GCodeProcessorResult* result);
    //BBS: set offset for gcode writer
-    void set_gcode_offset(double x, double y) { m_writer.set_xy_offset(x, y); m_processor.set_xy_offset(x, y);}
+    void set_gcode_offset(double x, double y) { m_gcode_offset = Vec2d(x, y); m_writer->set_xy_offset(x, y); m_processor.set_xy_offset(x, y);}

    // Exported for the helper classes (OozePrevention, Wipe) and for the Perl binding for unit tests.
    const Vec2d&    origin() const { return m_origin; }
@@ -237,8 +243,8 @@ public:
    Vec3d                    point_to_gcode_quantized(const Point3& point) const;
    const FullPrintConfig &config() const { return m_config; }
    const Layer*    layer() const { return m_layer; }
-    GCodeWriter&    writer() { return m_writer; }
-    const GCodeWriter& writer() const { return m_writer; }
+    GCodeWriter&    writer() { return *m_writer; }
+    const GCodeWriter& writer() const { return *m_writer; }
    PlaceholderParser& placeholder_parser() { return m_placeholder_parser_integration.parser; }
    const PlaceholderParser& placeholder_parser() const { return m_placeholder_parser_integration.parser; }
    // Process a template through the placeholder parser, collect error messages to be reported
@@ -261,7 +267,7 @@ public:
    bool            needs_retraction(const Polyline& travel, ExtrusionRole role, LiftType& lift_type);
    std::string     retract(bool toolchange = false, bool is_last_retraction = false, LiftType lift_type = LiftType::NormalLift, bool apply_instantly = false, ExtrusionRole role = erNone);
    // extra_retract forwards a PETG pre-extrusion over-extrusion; default 0 -> identical to the plain deretract.
-    std::string     unretract(float extra_retract = 0.f) { return m_writer.unlift() + m_writer.unretract(extra_retract); }
+    std::string     unretract(float extra_retract = 0.f) { return m_writer->unlift() + m_writer->unretract(extra_retract); }
    std::string     set_extruder(unsigned int extruder_id, double print_z, bool by_object=false, int toolchange_temp_override = -1, bool defer_temp_wait = false);
    bool is_BBL_Printer();
    WipeTowerType wipe_tower_type();
@@ -286,6 +292,13 @@ public:
        const Layer* 		object_layer;
        const SupportLayer* support_layer;
        const PrintObject*  original_object; //BBS: used for shared object logic
+        // Belt printers only: an apron band that prints BELOW the object's first
+        // layer, so it has no object or support layer of its own.  Deliberately
+        // not a Layer, so it cannot leak Layer::id() semantics into initial-layer
+        // temperature, spiral vase, cooling or interpolation logic.  When this is
+        // the only thing set, layer() is null and process_layer() takes its
+        // dedicated brim-only branch.
+        const BeltBrimBand* belt_brim_band { nullptr };
        const Layer* 		layer()   const
        {
            if (object_layer != nullptr)
@@ -315,11 +328,25 @@ public:
                count++;
            }

+            // A brim-only apron band contributes no object/support layer, and
+            // averaging zero terms would yield NaN.  Never folded into the
+            // average, so the non-belt result is bit-identical.
+            if (count == 0 && belt_brim_band != nullptr)
+                return belt_brim_band->print_z;
+
            return sum_z / count;
        }
    };

-private:
+    // Public accessor for the first-layer plane evaluator.  Used by
+    // CoolingBuffer (which is constructed with a GCode reference and needs
+    // to read the plane for per-segment fan re-evaluation).  All other
+    // first-layer-plane access points (on_first_layer overload, effective
+    // index helper) are in the protected section since they're called from
+    // GCode internals only.
+    const FirstLayerPlane *first_layer_plane() const { return m_first_layer_plane.get(); }
+
+protected:
    class GCodeOutputStream {
    public:
        GCodeOutputStream(FILE *f, GCodeProcessor &processor) : f(f), m_processor(processor) {}
@@ -347,9 +374,21 @@ private:
        FILE *f = nullptr;
        GCodeProcessor &m_processor;
    };
+
+    // Virtual hooks for belt printer subclass (BeltGCode).
+    // No-ops in base GCode; overridden in BeltGCode.
+    virtual void init_belt_writer(Print &print) {}
+    virtual void write_belt_header(GCodeOutputStream &file, const Print &print) {}
+    virtual void on_set_origin(const PrintObject *obj, const Point &inst_shift) {}
+    // Arc fitting is suppressed whenever the writer's machine mapping cannot
+    // represent a G2/G3 arc. Belt printers get this through BeltKinematics
+    // rather than through an override of their own.
+    virtual bool should_disable_arc_fitting() const
+        { return ! m_writer->kinematics().supports_arc_moves(); }
+
    void            _do_export(Print &print, GCodeOutputStream &file, ThumbnailsGeneratorCallback thumbnail_cb);

-    static std::vector<LayerToPrint>        		                   collect_layers_to_print(const PrintObject &object);
+    static std::vector<LayerToPrint>        		                   collect_layers_to_print(const PrintObject &object, bool skip_empty_first_layer = false);
    static std::vector<std::pair<coordf_t, std::vector<LayerToPrint>>> collect_layers_to_print(const Print &print);

    std::string generate_skirt(const Print &print,
@@ -369,7 +408,29 @@ private:
    std::string generate_object_brim(const Print &print,
        const PrintObject &object,
        size_t instance_id,
-        bool first_layer);
+        bool first_layer,
+        const Layer *object_layer);
+
+    // Belt printers: emit one brim-only apron layer.  These print below the
+    // object's first layer, so there is no object or support layer for the normal
+    // process_layer() machinery to work from.  Kept to the minimum a layer needs -
+    // tool, Z move, extrusions - so that nothing here can perturb the
+    // Layer::id()-based logic the ordinary path relies on.
+    LayerResult process_belt_brim_layer(
+        const Print                     &print,
+        const std::vector<LayerToPrint> &layers,
+        const LayerTools                &layer_tools,
+        const bool                       last_layer,
+        const size_t                     single_object_instance_idx);
+
+    // Emit the apron bands carried by these layers whose brim filament is extruder_id
+    // (0-based).  Called from both the brim-only branch and the ordinary path, since a
+    // band's print_z can coincide with another object's layer on a multi-object belt.
+    std::string emit_belt_brim_bands(
+        const Print                     &print,
+        const std::vector<LayerToPrint> &layers,
+        const size_t                     single_object_instance_idx,
+        const unsigned int               extruder_id);

    LayerResult process_layer(
        const Print                     &print,
@@ -572,9 +633,21 @@ private:
    };

    // Cache the per-filament island tour to avoid recomputing while the layer's island layout is
-    // unchanged. Key: filament_id. Value: {nodes the tour was computed from, resulting visits}.
-    std::map<unsigned int, std::pair<std::vector<IslandOrderNode>, std::vector<InstanceVisit>>>
-                                        m_ordering_cache;
+    // unchanged. Key: filament_id. Value: the nodes the tour was computed from, the per-instance
+    // island layout (count and whether the trailing catch-all island has anything to print), and
+    // the resulting visits.
+    // The layout is part of the key. Nodes only cover the chainable islands, so two
+    // layers with the same centroids but a different number of islands (thin walls, negative
+    // volumes come and go) matched the cache and the visit's catch-all index -- islands.size() - 1
+    // of the OLD layer -- ran past the new layer's islands (found by fuzzing: segfault in
+    // extrude_perimeters on multi-part objects).
+    struct IslandOrderCacheEntry
+    {
+        std::vector<IslandOrderNode>         nodes;
+        std::vector<std::pair<size_t, bool>> layout;
+        std::vector<InstanceVisit>           visits;
+    };
+    std::map<unsigned int, IslandOrderCacheEntry> m_ordering_cache;

    ExtrusionQualityEstimator m_extrusion_quality_estimator;

@@ -587,7 +660,7 @@ private:
    DynamicConfig                       m_calib_config;
    // scaled G-code resolution
    double                              m_scaled_resolution;
-    GCodeWriter                         m_writer;
+    std::unique_ptr<GCodeWriter>         m_writer;

    struct PlaceholderParserIntegration {
        void reset();
@@ -707,6 +780,13 @@ private:

    std::unique_ptr<CoolingBuffer>      m_cooling_buffer;
    std::unique_ptr<SpiralVase>         m_spiral_vase;
+    // First-layer plane evaluator.  Constructed once per print from the
+    // PrintConfig.  is_active() == false on non-belt printers and on belt
+    // printers without a Z-axis shear; in that case all per-path plane
+    // checks short-circuit to the legacy Layer::id() == 0 path.
+    std::unique_ptr<FirstLayerPlane>    m_first_layer_plane;
+    // Plate origin, kept so a writer replaced during export can be given it again.
+    Vec2d                               m_gcode_offset{ Vec2d::Zero() };

    std::unique_ptr<PressureEqualizer>  m_pressure_equalizer;
    
@@ -760,6 +840,25 @@ private:
    // resolvers. Distinct from m_layer_index (an export progress counter starting at -1).
    size_t m_cur_layer_idx{0};

+    // Belt brim apron layers only.  They have no Layer, so the print_z that
+    // _extrude() needs for the first-layer-plane probe is published here instead.
+    // Scoped by BeltBrimZGuard in process_belt_brim_layer(), never left set.
+    std::optional<coordf_t> m_belt_brim_z;
+    // Belt brim only.  Brim and coincident apron bands are emitted before m_layer
+    // is switched to their object, so belt_height_above_floor() would otherwise
+    // read the previously visited object's belt description -- making a brim's
+    // classification depend on plate visiting order.  Those paths publish the
+    // owner here for the duration of the emission.  Never left set.
+    const PrintObject *m_belt_floor_object{nullptr};
+    struct BeltFloorObjectGuard {
+        const PrintObject *&slot;
+        BeltFloorObjectGuard(const PrintObject *&s, const PrintObject *o) : slot(s) { slot = o; }
+        ~BeltFloorObjectGuard() { slot = nullptr; }
+    };
+
+    // The last extrusion segment was inside the belt's first-layer fan band (see _extrude()).
+    bool m_belt_in_band{false};
+
    std::set<unsigned int>                  m_initial_layer_extruders;
    std::vector<std::vector<unsigned int>>  m_sorted_layer_filaments;
    // BBS
@@ -777,6 +876,61 @@ private:
    // On the first printing layer. This flag triggers first layer speeds.
    //BBS
    bool    on_first_layer() const { return m_layer != nullptr && m_layer->id() == 0 && abs(m_layer->bottom_z()) < EPSILON; }
+    // Per-point first-layer test.  When the FirstLayerPlane evaluator is
+    // active, the result depends on the supplied slicing-frame point;
+    // otherwise we delegate to the legacy per-layer test.  This is the
+    // entry point used by per-path call sites in _extrude.
+    bool on_first_layer(const Vec3d &point_slicing_mm) const {
+        // Belt printers: measure height above the belt surface itself, in the
+        // slicing frame. See belt_height_above_floor() for why this does not go
+        // through FirstLayerPlane.
+        double h;
+        if (this->belt_height_above_floor(point_slicing_mm, h))
+            return h <= m_config.initial_layer_print_height.value + EPSILON;
+        if (m_first_layer_plane && m_first_layer_plane->is_active())
+            return m_first_layer_plane->is_first_layer(
+                point_slicing_mm, m_config.initial_layer_print_height.value);
+        return on_first_layer();
+    }
+    // "Effective layer index" used to drive layer-count thresholds like
+    // slow_down_layers.  When the evaluator is active this returns the
+    // perpendicular distance to the plane in band_thickness_mm units;
+    // otherwise it returns the legacy slicing layer index.
+    int effective_layer_index_for_point(const Vec3d &point_slicing_mm) const {
+        double h;
+        if (this->belt_height_above_floor(point_slicing_mm, h)) {
+            const double lh = this->first_layer_band_mm();
+            return h <= 0. ? 0 : int(std::floor(h / lh));
+        }
+        if (m_first_layer_plane && m_first_layer_plane->is_active())
+            return m_first_layer_plane->effective_layer_index(point_slicing_mm);
+        return on_first_layer() ? 0 : layer_id();
+    }
+
+    // Band thickness for the *effective layer index* only.  FirstLayerPlane keeps
+    // two separate thresholds and so must this path: is_first_layer() tests
+    // against initial_layer_print_height, while effective_layer_index() counts
+    // bands of first_layer_plane_thickness.  Conflating them would apply
+    // first-layer treatment through a whole 1mm band on a 0.2mm first layer.
+    double first_layer_band_mm() const {
+        double band = m_config.first_layer_plane_thickness.value;
+        if (band <= 0.) band = m_config.initial_layer_print_height.value;
+        return band > 0. ? band : 0.2;
+    }
+
+    // Height of a slicing-frame point above the belt surface, or false when this
+    // is not a belt print.
+    //
+    // The belt surface is known exactly in the slicing frame from the slicing
+    // parameters (belt_floor_shear_factor / _from_axis / _z_shift) -- the same
+    // description the support generator uses. FirstLayerPlane instead derives its
+    // plane by composing gcode_remap_* with the g-code back-transform, so its
+    // answer changes with the machine's *output* axis convention: on a printer
+    // with a non-identity remap it reported ~86mm of clearance for geometry
+    // sitting directly on the belt, and no extrusion was ever classified as
+    // first-layer. Measuring against the belt itself is independent of every
+    // remap and back-transform.
+    bool belt_height_above_floor(const Vec3d &point_slicing_mm, double &height_mm) const;
    int layer_id() const {
        if (m_layer == nullptr)
            return -1;
@@ -0,0 +1,40 @@
+#include "BeltBackTransform.hpp"
+#include "../BeltTransform.hpp"
+
+namespace Slic3r {
+
+bool BeltBackTransform::init_from_config(const PrintConfig &config)
+{
+    m_active  = false;
+    m_inverse = Transform3d::Identity();
+
+    if (!config.belt_printer.value || !config.gcode_back_transform.value)
+        return false;
+
+    // Require at least one active transform to proceed.
+    bool has_global_rotation = config.belt_slice_rotation_global.value
+                            && config.belt_slice_rotation.value != BeltRotationAxis::None;
+    bool has_preslice_global = config.belt_preslice_global.value
+                            || config.preslice_remap_global.value;
+    if (!has_global_rotation && !has_preslice_global
+        && !BeltTransformPipeline::has_preslice_remap(config))
+        return false;
+
+    // Build the forward pipeline (rotation * pre_remap) and store its inverse.
+    Transform3d forward = BeltTransformPipeline::build_forward_transform(config);
+    if (forward.isApprox(Transform3d::Identity()))
+        return false;
+
+    m_inverse = forward.inverse();
+    m_active  = true;
+    return true;
+}
+
+Vec3d BeltBackTransform::apply(const Vec3d &pos) const
+{
+    if (!m_active)
+        return pos;
+    return m_inverse * pos;
+}
+
+} // namespace Slic3r
@@ -0,0 +1,45 @@
+#ifndef slic3r_BeltBackTransform_hpp_
+#define slic3r_BeltBackTransform_hpp_
+
+#include "../libslic3r.h"
+#include "../Point.hpp"
+#include "../PrintConfig.hpp"
+
+namespace Slic3r {
+
+// Reverses the pre-slice remap + shear + scale transforms that
+// PrintObjectSlice.cpp applies to belt printer geometry, converting G-code
+// coordinates from the sliced (remapped/sheared/scaled) frame back to the
+// machine's real coordinate space.
+//
+// Initialized once from PrintConfig, then applied per-point in
+// BeltKinematics::to_machine() before axis remapping.
+//
+// Active when gcode_back_transform is true AND at least one of:
+//   - a shear axis has global mode enabled, or
+//   - a pre-slice axis remap is non-identity.
+class BeltBackTransform
+{
+public:
+    BeltBackTransform() = default;
+
+    // Initialize from belt printer config.  Rebuilds the same pre-slice remap,
+    // shear, and scale matrices as PrintObjectSlice.cpp and precomputes the
+    // affine inverse.  Returns true if a non-identity back-transform was computed.
+    bool init_from_config(const PrintConfig &config);
+
+    // Apply the inverse transform to a point.  Returns pos unchanged if
+    // no back-transform is active.
+    Vec3d apply(const Vec3d &pos) const;
+
+    // True if a non-identity back-transform is active.
+    bool is_active() const { return m_active; }
+
+private:
+    bool       m_active  = false;
+    Transform3d m_inverse = Transform3d::Identity();
+};
+
+} // namespace Slic3r
+
+#endif // slic3r_BeltBackTransform_hpp_
@@ -0,0 +1,40 @@
+#include "BeltKinematics.hpp"
+#include "../BeltTransform.hpp"
+#include "../PrintConfig.hpp"
+#include "../GCodeWriter.hpp"
+
+namespace Slic3r {
+
+BeltKinematics::BeltKinematics(const PrintConfig &config, bool world_coordinates)
+    : m_world_coordinates(world_coordinates)
+{
+    m_back_active = m_back_transform.init_from_config(config);
+    m_machine_frame.init_from_config(config);
+    if (m_back_active)
+        // BeltBackTransform stores the inverse of this; keep the forward so
+        // to_logical() can reverse the whole chain.
+        m_back_forward = BeltTransformPipeline::build_forward_transform(config);
+}
+
+Vec3d BeltKinematics::to_machine(const Vec3d &p) const
+{
+    const Vec3d after_back  = m_world_coordinates ? p : m_back_transform.apply(p);
+    const Vec3d after_remap = this->apply_axis_remap(after_back);
+    return m_machine_frame.apply(after_remap);
+}
+
+Vec3d BeltKinematics::to_logical(const Vec3d &machine) const
+{
+    const Vec3d before_frame = m_machine_frame.apply_inverse(machine);
+    const Vec3d before_remap = this->apply_axis_remap_inverse(before_frame);
+    if (m_world_coordinates || ! m_back_active)
+        return before_remap;
+    return m_back_forward * before_remap;
+}
+
+void install_belt_kinematics(GCodeWriter &writer, const PrintConfig &config, bool world_coordinates)
+{
+    writer.set_kinematics(std::make_unique<BeltKinematics>(config, world_coordinates));
+}
+
+} // namespace Slic3r
@@ -0,0 +1,69 @@
+#ifndef slic3r_BeltKinematics_hpp_
+#define slic3r_BeltKinematics_hpp_
+
+#include "MachineKinematics.hpp"
+#include "BeltBackTransform.hpp"
+#include "MachineFrameTransform.hpp"
+
+namespace Slic3r {
+
+class PrintConfig;
+class GCodeWriter;
+
+// Belt-printer machine frame.
+//
+// Forward order, as applied per emitted point:
+//     machine = MachineFrameTransform( axis_remap( BeltBackTransform( logical ) ) )
+//
+// i.e. the slicer->world back-transform runs FIRST and the machine-frame
+// shear/scale LAST, so the latter acts as a global linear transform on the
+// already-placed coordinates.
+//
+// world_coordinates mode (the PA line / PA pattern calibration generators)
+// treats the incoming point as already relative to the belt surface -- X across,
+// Y along the belt, Z above it -- and therefore skips the back-transform while
+// keeping the remap and the machine frame. It is a different coordinate map, not
+// a writer mode, which is why it is fixed at construction.
+class BeltKinematics : public CartesianKinematics
+{
+public:
+    explicit BeltKinematics(const PrintConfig &config, bool world_coordinates = false);
+
+    Vec3d to_machine(const Vec3d &p) const override;
+    Vec3d to_logical(const Vec3d &machine) const override;
+    // Machine -> build-volume frame. Only the machine-frame shear/scale is undone,
+    // matching what GCodeProcessor's bounds validation wants. This is deliberately
+    // NOT to_logical().
+    Vec3d to_build_volume(const Vec3d &machine) const override
+        { return m_machine_frame.apply_inverse(machine); }
+
+    // A belt writer has always emitted full XYZ on every move, whether or not any
+    // individual stage reports itself active. Making this conditional would change
+    // emitted G-code for an identity-transform belt configuration.
+    bool must_emit_all_axes() const override { return true; }
+    bool suppress_lift_at_unknown_position() const override { return true; }
+    // The machine frame shears and scales, so a circle is an ellipse in machine
+    // coordinates and G2/G3 cannot describe it.
+    bool supports_arc_moves() const override { return false; }
+
+    bool world_coordinates() const { return m_world_coordinates; }
+
+private:
+    BeltBackTransform     m_back_transform;
+    MachineFrameTransform m_machine_frame;
+    // Forward of what m_back_transform inverts, kept so to_logical() can undo it.
+    Transform3d           m_back_forward { Transform3d::Identity() };
+    bool                  m_back_active { false };
+    bool                  m_world_coordinates { false };
+};
+
+// Install a belt machine frame on any GCodeWriter. Any axis remap and build
+// volume already configured on the writer are carried over, so this may be
+// called before or after those setters. Re-calling it with a different
+// world_coordinates value swaps the map (used around the PA line generator).
+void install_belt_kinematics(GCodeWriter &writer, const PrintConfig &config,
+                             bool world_coordinates = false);
+
+} // namespace Slic3r
+
+#endif // slic3r_BeltKinematics_hpp_
@@ -3,8 +3,11 @@
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/algorithm/string/replace.hpp>
 #include <boost/log/trivial.hpp>
+#include <algorithm>
+#include <cstdlib>
 #include <iostream>
 #include <float.h>
+#include <string_view>
 #include <system_error>
 #include <unordered_map>

@@ -28,10 +31,12 @@ CoolingBuffer::CoolingBuffer(GCode &gcodegen) : m_config(gcodegen.config()), m_t
        m_num_extruders = std::max(ex.id() + 1, m_num_extruders);
        m_extruder_ids.emplace_back(ex.id());
    }
+
 }

 void CoolingBuffer::reset(const Vec3d &position)
 {
+    m_belt_band_active = false;
    // BBS: add I and J axis to store center of arc
    m_current_pos.assign(7, 0.f);
    m_current_pos[0] = float(position.x());
@@ -71,6 +76,9 @@ struct CoolingLine
        // ORCA: Add support for ironing fan speed control
        TYPE_IRONING_FAN_START         = 1 << 19,
        TYPE_IRONING_FAN_END           = 1 << 20,
+        // Belt printers: extrusions within the first-layer band above the belt.
+        TYPE_BELT_BAND_START           = 1 << 21,
+        TYPE_BELT_BAND_END             = 1 << 22,
    };

    CoolingLine(unsigned int type, size_t  line_start, size_t  line_end) :
@@ -531,6 +539,10 @@ std::vector<PerExtruderAdjustments> CoolingBuffer::parse_layer_gcode(const std::
            line.type = CoolingLine::TYPE_IRONING_FAN_START;
        } else if (boost::starts_with(sline, ";_IRONING_FAN_END")) { // ORCA: Add support for ironing fan speed control
            line.type = CoolingLine::TYPE_IRONING_FAN_END;
+        } else if (boost::starts_with(sline, ";_BELT_BAND_START")) {
+            line.type = CoolingLine::TYPE_BELT_BAND_START;
+        } else if (boost::starts_with(sline, ";_BELT_BAND_END")) {
+            line.type = CoolingLine::TYPE_BELT_BAND_END;
        } else if (boost::starts_with(sline, "G4 ")) {
            // Parse the wait time.
            line.type = CoolingLine::TYPE_G4;
@@ -872,7 +884,9 @@ std::string CoolingBuffer::apply_layer_cooldown(
                                                               {CoolingLine::TYPE_SUPPORT_INTERFACE_FAN_START, false},
                                                               {CoolingLine::TYPE_IRONING_FAN_START, false}, // ORCA: Add support for ironing fan speed control
                                                               {CoolingLine::TYPE_FORCE_RESUME_FAN, false}};
-    bool need_set_fan = false;
+    // Belt printers: a band still open from the previous layer has to take the fan back from
+    // the layer-level speed issued just above.
+    bool need_set_fan = m_belt_band_active;

    for (const CoolingLine *line : lines) {
        const char *line_start  = gcode.c_str() + line->line_start;
@@ -886,6 +900,8 @@ std::string CoolingBuffer::apply_layer_cooldown(
                if (new_extruder != m_current_extruder) {
                    m_current_extruder = new_extruder;
                    change_extruder_set_fan(true);
+                    if (m_belt_band_active)
+                        need_set_fan = true;
                }
            }
            new_gcode.append(line_start, line_end - line_start);
@@ -938,6 +954,13 @@ std::string CoolingBuffer::apply_layer_cooldown(
            if (m_additional_fan_speed != -1 && m_config.auxiliary_fan.value)
                new_gcode += GCodeWriter::set_additional_fan(m_additional_fan_speed);
        }
+        else if (line->type & CoolingLine::TYPE_BELT_BAND_START) {
+            m_belt_band_active = true;
+            need_set_fan       = true;
+        } else if (line->type & CoolingLine::TYPE_BELT_BAND_END) {
+            m_belt_band_active = false;
+            need_set_fan       = true;
+        }
        else if (line->type & CoolingLine::TYPE_EXTRUDE_END) {
            // Just remove this comment.
        } else if (line->type & (CoolingLine::TYPE_ADJUSTABLE | CoolingLine::TYPE_EXTERNAL_PERIMETER | CoolingLine::TYPE_WIPE | CoolingLine::TYPE_HAS_F)) {
@@ -1030,7 +1053,15 @@ std::string CoolingBuffer::apply_layer_cooldown(
                    m_current_fan_speed = speed;
                }
            };
-            if (fan_speed_change_requests[CoolingLine::TYPE_OVERHANG_FAN_START]){
+            if (m_belt_band_active) {
+                // Belt printers: a tilted layer runs from the belt to the top of the part, so
+                // "the first layers" are a band along the belt rather than the first slicing
+                // layers. Extrusions GCode::_extrude() marks as inside that band print with the
+                // fan off, whatever overhang, bridge or resume request is pending, as the first
+                // layers of a flat bed do. Leaving the band falls through to the branches below.
+                set_fan(0);
+                fan_speed_change_requests[CoolingLine::TYPE_FORCE_RESUME_FAN] = false;
+            } else if (fan_speed_change_requests[CoolingLine::TYPE_OVERHANG_FAN_START]){
                set_fan(overhang_fan_speed);
            } else if (fan_speed_change_requests[CoolingLine::TYPE_INTERNAL_BRIDGE_FAN_START]){ // ORCA: Add support for separate internal bridge fan speed control
                set_fan(internal_bridge_fan_speed);
@@ -18,7 +18,7 @@ struct PerExtruderAdjustments;
 //
 // The simple it sounds, the actual implementation is significantly more complex.
 // Namely, for a multi-extruder print, each material may require a different cooling logic.
-// For example, some materials may not like to print too slowly, while with some materials 
+// For example, some materials may not like to print too slowly, while with some materials
 // we may slow down significantly.
 //
 class CoolingBuffer {
@@ -58,6 +58,9 @@ private:
    unsigned int                m_current_nozzle;
    //BBS: current fan speed
    int                         m_current_fan_speed;
+    // Belt printers: the extrusion being processed lies in the first-layer band above the
+    // belt (between a ";_BELT_BAND_START" and a ";_BELT_BAND_END"). Kept across layers.
+    bool                        m_belt_band_active = false;
 };

 }
@@ -2533,6 +2533,12 @@ void GCodeProcessorResult::reset() {
    long_retraction_when_cut = false;
    timelapse_warning_code = 0;
    printable_height = 0.0f;
+    machine_frame_transform_active = false;
+    belt_tilt_angle = 0.f;
+    belt_z_origin   = 0.f;
+    preslice_remap_x = RemapAxis::PosX;
+    preslice_remap_y = RemapAxis::PosY;
+    preslice_remap_z = RemapAxis::PosZ;
    settings_ids.reset();
    filaments_count = 0;
    backtrace_enabled = false;
@@ -2769,6 +2775,32 @@ bool GCodeProcessor::check_multi_extruder_gcode_valid(const int
        return ps;
    };

+    // Belt-printer post-gcode shear/scale/post_remap is applied as the final
+    // step of BeltKinematics::to_machine, so MoveVertex.position is
+    // in the printer's machine frame.  Undo it here so the XY area check
+    // operates in the build-volume frame that printable_area is defined in
+    // (the height checks below are skipped on belt printers).  For non-belt printers
+    // (is_active() == false) apply_inverse is identity and behaviour is
+    // unchanged from before.
+    const bool machine_frame_active = m_machine_frame_transform.is_active();
+    auto compare_pos = [&](const GCodeProcessorResult::MoveVertex &move) -> Vec3d {
+        Vec3d pos = move.position.cast<double>();
+        if (!machine_frame_active)
+            return pos;
+        Vec3d extruder_off = Vec3d::Zero();
+        if (size_t(move.extruder_id) < m_extruder_offsets.size())
+            extruder_off = m_extruder_offsets[move.extruder_id].cast<double>();
+        // Strip plate + extruder offsets to recover the raw machine-frame
+        // coordinate that was emitted into the G-code (see store_move_vertex).
+        Vec3d machine(pos.x() - m_x_offset - extruder_off.x(),
+                      pos.y() - m_y_offset - extruder_off.y(),
+                      pos.z() - extruder_off.z() + m_z_offset);
+        Vec3d build = m_machine_frame_transform.apply_inverse(machine);
+        // Re-apply plate offset so the result matches plate_printable_poly,
+        // which is translated by plate_offset below.
+        return Vec3d(build.x() + m_x_offset, build.y() + m_y_offset, build.z());
+    };
+
    struct GCodePosInfo
    {
        Points pos;
@@ -2780,26 +2812,20 @@ bool GCodeProcessor::check_multi_extruder_gcode_valid(const int
    for (const GCodeProcessorResult::MoveVertex &move : m_result.moves) {
        // sometimes, the start line extrude was outside the edge of plate a little, this is allowed, so do not include into the gcode_path_pos
        if (move.type == EMoveType::Extrude /* && move.extrusion_role != ExtrusionRole::erFlush || move.type == EMoveType::Travel*/) {
+            const Vec3d cp = compare_pos(move);
+            // For belt printers we read Z from the inverse-transformed position
+            // (post-origin-snap, pre-machine-frame).  Otherwise keep the
+            // original print_z source (the slicer's layer-Z comment) so
+            // non-belt behaviour is bit-for-bit unchanged.
+            const float z_for_height = machine_frame_active ? float(cp.z()) : move.print_z;
            if (move.extrusion_role == ExtrusionRole::erCustom) {
-                /*if (move.is_arc_move_with_interpolation_points()) {
-                    for (int i = 0; i < move.interpolation_points.size(); i++) {
-                        gcode_path_pos[move.object_label_id][int(move.extruder_id)].pos_custom.emplace_back(to_2d(move.interpolation_points[i].cast<double>()));
-                    }
-                } else {*/
-                    gcode_path_pos[move.object_label_id][int(move.extruder_id)].pos_custom.emplace_back(to_2d(move.position.cast<double>()));
-                //}
+                gcode_path_pos[move.object_label_id][int(move.extruder_id)].pos_custom.emplace_back(to_2d(cp));
                gcode_path_pos[move.object_label_id][int(move.extruder_id)].max_print_z_custom =
-                    std::max(gcode_path_pos[move.object_label_id][int(move.extruder_id)].max_print_z_custom, move.print_z);
+                    std::max(gcode_path_pos[move.object_label_id][int(move.extruder_id)].max_print_z_custom, z_for_height);
            } else {
-                /*if (move.is_arc_move_with_interpolation_points()) {
-                    for (int i = 0; i < move.interpolation_points.size(); i++) {
-                        gcode_path_pos[move.object_label_id][int(move.extruder_id)].pos.emplace_back(to_2d(move.interpolation_points[i].cast<double>()));
-                    }
-                } else {*/
-                    gcode_path_pos[move.object_label_id][int(move.extruder_id)].pos.emplace_back(to_2d(move.position.cast<double>()));
-                //}
+                gcode_path_pos[move.object_label_id][int(move.extruder_id)].pos.emplace_back(to_2d(cp));
                gcode_path_pos[move.object_label_id][int(move.extruder_id)].max_print_z = std::max(gcode_path_pos[move.object_label_id][int(move.extruder_id)].max_print_z,
-                                                                                                   move.print_z);
+                                                                                                   z_for_height);
            }
        }
    }
@@ -2834,7 +2860,12 @@ bool GCodeProcessor::check_multi_extruder_gcode_valid(const int
                    valid = false;
                }
            }
-            if ( iter->second.max_print_z > plate_printable_height ) { //over height
+            // Belt printers: the Z recorded here grows with belt travel (machine Z with the
+            // frame transform, the slicing-frame Z without it), while printable_height is the
+            // clearance above the belt; the two are not comparable, so the over-height check
+            // is skipped, as the preview's ToolHeightOutside warning already is.
+            // Print::validate() checks the object's height against the clearance.
+            if ( !m_belt_printer && iter->second.max_print_z > plate_printable_height ) { //over height
                m_result.gcode_check_result.error_code |= (1 << 3);
                std::pair<int, int> filament_to_object_id;
                filament_to_object_id.first  = iter->first;
@@ -2875,7 +2906,7 @@ bool GCodeProcessor::check_multi_extruder_gcode_valid(const int
                    }

                // check printable height
-                if ((extruder_id < printable_heights.size()) && (iter->second.max_print_z > printable_heights[extruder_id])) {
+                if (!m_belt_printer && (extruder_id < printable_heights.size()) && (iter->second.max_print_z > printable_heights[extruder_id])) {
                    m_result.gcode_check_result.error_code |= (1 << 1);
                    std::pair<int, int> filament_to_object_id;
                    filament_to_object_id.first  = iter->first;
@@ -3041,6 +3072,13 @@ void GCodeProcessor::apply_config(const PrintConfig& config)

    m_result.printable_height = config.printable_height;

+    // Belt printer: cache the post-gcode machine-frame transform so the
+    // multi-extruder validator can undo it and compare against build-volume
+    // bounds rather than machine-frame positions.
+    m_machine_frame_transform.init_from_config(config);
+    m_result.machine_frame_transform_active = m_machine_frame_transform.is_active();
+    m_belt_printer = config.belt_printer.value;
+
    auto filament_maps = config.option<ConfigOptionInts>("filament_map");
    if (filament_maps != nullptr) {
        m_filament_maps = filament_maps->values;
@@ -3554,6 +3592,7 @@ void GCodeProcessor::reset()
    m_zero_layer_height = 0.0f;
    m_first_layer_height = 0.0f;
    m_processing_start_custom_gcode = false;
+    m_in_config_block = false;
    m_g1_line_id = 0;
    m_layer_id = 0;
    m_cp_color.reset();
@@ -4159,6 +4198,55 @@ void GCodeProcessor::process_tags(const std::string_view comment, bool producers
        return;
    }

+    if (boost::starts_with(comment, " CONFIG_BLOCK_START")) {
+        m_in_config_block = true;
+        return;
+    }
+    if (boost::starts_with(comment, " CONFIG_BLOCK_END")) {
+        m_in_config_block = false;
+        return;
+    }
+
+    // Belt printer: derive the physical tilt magnitude from the slicing-rotation
+    // angle header comment (used to enable the preview's belt view). Only the belt
+    // header carries it outside the config block; the config block lists the key
+    // for every printer, belt or not.
+    if (!m_in_config_block && boost::starts_with(comment, " belt_slice_rotation_angle = ")) {
+        try {
+            m_result.belt_tilt_angle = std::abs(std::stof(std::string(comment.substr(29))));
+        } catch (...) {}
+        return;
+    }
+    // Belt printer: parse pre-slice axis remap from header comments.
+    {
+        auto trim = [](const std::string &s) -> std::string {
+            size_t start = s.find_first_not_of(" \t\r\n");
+            size_t end   = s.find_last_not_of(" \t\r\n");
+            return (start == std::string::npos) ? "" : s.substr(start, end - start + 1);
+        };
+        // Pre-slice axis remap
+        auto parse_remap_axis = [](const std::string &s) -> RemapAxis {
+            if (s == "pos_x") return RemapAxis::PosX;
+            if (s == "pos_y") return RemapAxis::PosY;
+            if (s == "pos_z") return RemapAxis::PosZ;
+            if (s == "neg_x") return RemapAxis::NegX;
+            if (s == "neg_y") return RemapAxis::NegY;
+            if (s == "neg_z") return RemapAxis::NegZ;
+            if (s == "rev_x") return RemapAxis::RevX;
+            if (s == "rev_y") return RemapAxis::RevY;
+            if (s == "rev_z") return RemapAxis::RevZ;
+            return RemapAxis::PosX;
+        };
+        if (boost::starts_with(comment, " preslice_remap_x = ")) {
+            m_result.preslice_remap_x = parse_remap_axis(trim(std::string(comment.substr(20)))); return;
+        }
+        if (boost::starts_with(comment, " preslice_remap_y = ")) {
+            m_result.preslice_remap_y = parse_remap_axis(trim(std::string(comment.substr(20)))); return;
+        }
+        if (boost::starts_with(comment, " preslice_remap_z = ")) {
+            m_result.preslice_remap_z = parse_remap_axis(trim(std::string(comment.substr(20)))); return;
+        }
+    }
    // wipe start tag
    if (boost::starts_with(comment, reserved_tag(ETags::Wipe_Start))) {
        m_wiping = true;
@@ -6055,6 +6143,13 @@ void GCodeProcessor::process_G92(const GCodeReader::GCodeLine& line)
    if (line.has_z()) {
        m_origin[Z] = m_end_position[Z] - line.z() * lengths_scale_factor;
        any_found = true;
+        // Belt only: the start G-code's purge-blob advance + G92 Z0 resets leave a constant
+        // machine-Z origin offset here; the designed-view back-transform subtracts it so
+        // toolpaths map to the model's belt coordinate (gcode Z). Gated on belt_tilt_angle
+        // (set from the belt header, parsed before the body) so non-belt G-code processing
+        // is byte-identical — no unconditional work on the shared path.
+        if (m_result.belt_tilt_angle != 0.f)
+            m_result.belt_z_origin = m_origin[Z];
    }

    if (line.has_e()) {
@@ -7033,6 +7128,22 @@ void GCodeProcessor::store_move_vertex(EMoveType type, EMovePathType path_type,
        m_result.print_statistics.total_travel_distance += m_travel_dist;
    }

+    // During the start G-code "prepare" stage the toolhead Z is not yet a real
+    // print height on a normal printer, so it is pinned to the first-layer height
+    // to keep the preview tidy. Belt printers are the exception: there the Z is
+    // written explicitly by the belt kinematics and the designed-view back-transform
+    // couples machine Z into the rendered model Y (the belt tilt mixes the height
+    // and belt-feed axes). Overriding Z therefore back-transforms the last
+    // prepare-stage move (the unretract before the first extrusion) to model
+    // Y ~= 0, and the libvgcode path builder then draws a phantom extrusion
+    // segment from Y ~= 0 to the first real toolpath. Keep the real Z for belt
+    // printers so prepare-stage moves map correctly. Gated on belt_tilt_angle (set
+    // from the G-code header before the body is processed) so non-belt processing
+    // is byte-identical.
+    const float store_z = (m_processing_start_custom_gcode && m_result.belt_tilt_angle == 0.f)
+        ? m_first_layer_height
+        : m_end_position[Z] - m_z_offset;
+
    m_result.moves.push_back({
        m_last_line_id,
        type,
@@ -7040,7 +7151,7 @@ void GCodeProcessor::store_move_vertex(EMoveType type, EMovePathType path_type,
        static_cast<unsigned char>(filament_id),
        m_cp_color.current,
        //BBS: add plate's offset to the rendering vertices
-        Vec3f(m_end_position[X] + m_x_offset, m_end_position[Y] + m_y_offset, m_processing_start_custom_gcode ? m_first_layer_height : m_end_position[Z]- m_z_offset) + m_extruder_offsets[filament_id],
+        Vec3f(m_end_position[X] + m_x_offset, m_end_position[Y] + m_y_offset, store_z) + m_extruder_offsets[filament_id],
        static_cast<float>(m_end_position[E] - m_start_position[E]),
        m_feedrate,
        0.0f, // actual feedrate
@@ -7,6 +7,7 @@
 #include "libslic3r/PrintConfig.hpp"
 #include "libslic3r/CustomGCode.hpp"
 #include "libslic3r/MultiNozzleUtils.hpp"
+#include "libslic3r/GCode/MachineFrameTransform.hpp"

 #include <cstdint>
 #include <array>
@@ -276,6 +277,22 @@ class Print;
        bool support_traditional_timelapse{true};
        float printable_height;
        float z_offset;
+        // Belt printer: physical tilt magnitude (deg) parsed from the slicing-rotation
+        // header comment; used to enable the preview's belt view.
+        float belt_tilt_angle{ 0.f };
+        // Belt printer: machine-Z origin offset (mm) left in m_origin[Z] by the start
+        // G-code (purge-blob belt advance + G92 Z0 resets). Move positions are stored
+        // as gcode_Z + this offset, so the designed-view back-transform must subtract it
+        // to recover the model's belt coordinate.
+        float belt_z_origin{ 0.f };
+        // Belt printer: post-gcode shear/scale/post_remap is configured and
+        // non-identity.  When set, the layer Z values in `moves` are in the
+        // machine frame and should not be compared against `printable_height`
+        // (which lives in the build-volume frame).
+        bool machine_frame_transform_active{ false };
+        RemapAxis preslice_remap_x{ RemapAxis::PosX };
+        RemapAxis preslice_remap_y{ RemapAxis::PosY };
+        RemapAxis preslice_remap_z{ RemapAxis::PosZ };
        SettingsIds settings_ids;
        size_t filaments_count;
        bool backtrace_enabled;
@@ -367,6 +384,12 @@ class Print;
            // Keep the SKIPPABLE per-type time on a copied result.
            skippable_part_time = other.skippable_part_time;
            initial_layer_time = other.initial_layer_time;
+            belt_tilt_angle = other.belt_tilt_angle;
+            belt_z_origin = other.belt_z_origin;
+            machine_frame_transform_active = other.machine_frame_transform_active;
+            preslice_remap_x = other.preslice_remap_x;
+            preslice_remap_y = other.preslice_remap_y;
+            preslice_remap_z = other.preslice_remap_z;
 #if ENABLE_GCODE_VIEWER_STATISTICS
            time = other.time;
 #endif
@@ -1136,6 +1159,13 @@ class Print;
        double          m_x_offset{ 0 };
        double          m_y_offset{ 0 };

+        // Belt-printer post-gcode shear/scale/post_remap. Used by
+        // check_multi_extruder_gcode_valid to undo the machine-frame
+        // transform on move positions so bounds checks operate in the
+        // pre-machine-frame (build-volume) frame.
+        MachineFrameTransform m_machine_frame_transform;
+        bool                  m_belt_printer{ false };
+
        unsigned int m_line_id;
        unsigned int m_last_line_id;
        float m_feedrate; // mm/s
@@ -1165,6 +1195,7 @@ class Print;
        float m_first_layer_height; // mm
        float m_zero_layer_height; // mm
        bool m_processing_start_custom_gcode;
+        bool m_in_config_block;
        unsigned int m_g1_line_id;
        unsigned int m_layer_id;
        CpColor m_cp_color;
@@ -0,0 +1,86 @@
+#include "MachineFrameTransform.hpp"
+#include "../Geometry.hpp"
+
+#include <cmath>
+
+namespace Slic3r {
+
+bool MachineFrameTransform::init_from_config(const PrintConfig &config)
+{
+    m_active            = false;
+    m_transform         = Transform3d::Identity();
+    m_transform_inverse = Transform3d::Identity();
+
+    if (!config.belt_printer.value)
+        return false;
+
+    // The machine-frame transform is derived from the single belt tilt (axis +
+    // angle) that also drives the pre-slice mesh rotation.  Expert decouple lets
+    // the machine-frame angle differ from the slicing rotation; otherwise both
+    // use belt_slice_rotation_angle.
+    const BeltRotationAxis axis = config.belt_slice_rotation.value;
+    if (axis == BeltRotationAxis::None || axis == BeltRotationAxis::Z)
+        return false; // Z is an in-plane spin: no machine-frame tilt.
+
+    const double angle_deg = config.belt_frame_tilt_decouple.value
+        ? config.belt_frame_tilt_angle.value
+        : config.belt_slice_rotation_angle.value;
+    if (std::abs(angle_deg) <= EPSILON)
+        return false;
+
+    const double angle_rad = Geometry::deg2rad(angle_deg);
+    const double sin_a      = std::sin(angle_rad);
+    if (std::abs(sin_a) <= EPSILON)
+        return false;
+    const double cot_a   = std::cos(angle_rad) / sin_a;
+    const double inv_sin = 1.0 / std::abs(sin_a);
+
+    // This stage runs after the conventional belt axis swap. For an X-axis
+    // slicing rotation, remapped Y is model height and remapped Z is travel
+    // along the belt. Convert those Cartesian coordinates to machine axes with
+    // the established belt-printer convention:
+    //   machine gantry = model height / sin(a)
+    //   machine belt   = model belt + model height * cot(a)
+    // The Y-rotation case is the same mapping on X/Z, with the rotation sign.
+    // At 45 degrees tan/cot and sin/cos are equal, which previously hid the
+    // incorrect complementary-angle formulas used by this unified transform.
+    Matrix3d shear = Matrix3d::Identity();
+    Matrix3d scale = Matrix3d::Identity();
+    if (axis == BeltRotationAxis::X) {
+        shear(2, 1) =  cot_a;   // Z from Y
+        scale(1, 1) =  inv_sin; // Y
+    } else { // BeltRotationAxis::Y
+        shear(2, 0) = -cot_a;   // Z from X
+        scale(0, 0) =  inv_sin; // X
+    }
+
+    // Apply shear first, then scale (the historical default ShearThenScale order:
+    // result = scale * shear * p).  For the canonical 45°/X belt this maps
+    // (x,y,z) -> (x, y/sin, y + z), matching the previous per-axis config.
+    Transform3d combined = Transform3d::Identity();
+    combined.linear() = scale * shear;
+
+    if (combined.isApprox(Transform3d::Identity()))
+        return false;
+
+    m_transform         = combined;
+    m_transform_inverse = combined.inverse();
+    m_active            = true;
+    return true;
+}
+
+Vec3d MachineFrameTransform::apply(const Vec3d &pos) const
+{
+    if (!m_active)
+        return pos;
+    return m_transform * pos;
+}
+
+Vec3d MachineFrameTransform::apply_inverse(const Vec3d &pos) const
+{
+    if (!m_active)
+        return pos;
+    return m_transform_inverse * pos;
+}
+
+} // namespace Slic3r
@@ -0,0 +1,54 @@
+#ifndef slic3r_MachineFrameTransform_hpp_
+#define slic3r_MachineFrameTransform_hpp_
+
+#include "../libslic3r.h"
+#include "../Point.hpp"
+#include "../PrintConfig.hpp"
+
+namespace Slic3r {
+
+// Post-stage machine-frame transform for belt printers.
+//
+// Applied in BeltKinematics::to_machine AFTER the back-transform and
+// the gcode_remap_* axis remap.  Maps Cartesian (axis-permuted) G-code
+// coordinates into the printer's physical machine frame.
+//
+// Derived entirely from the single belt tilt (belt_slice_rotation axis +
+// belt_slice_rotation_angle): a shear coupling the height axis to the belt-feed
+// axis (factor cot a) plus a 1/sin a scale on the gantry-height axis.  The expert
+// belt_frame_tilt_decouple flag lets the machine-frame angle differ from the
+// pre-slice rotation angle via belt_frame_tilt_angle.
+class MachineFrameTransform
+{
+public:
+    MachineFrameTransform() = default;
+
+    // Initialize from belt printer config.  Returns true if a non-identity
+    // transform was computed.  Inactive when belt_printer is disabled or
+    // both shear and scale are identity.
+    bool init_from_config(const PrintConfig &config);
+
+    // Apply the transform to a point.  Returns pos unchanged if not active.
+    Vec3d apply(const Vec3d &pos) const;
+
+    // Apply the inverse transform.  Returns pos unchanged if not active.
+    // Used by validators that need to compare emitted machine-frame
+    // coordinates against build-volume bounds.
+    Vec3d apply_inverse(const Vec3d &pos) const;
+
+    bool is_active() const { return m_active; }
+
+    // The composed shear*scale transform (identity when inactive). Exposed so the
+    // G-code viewer can build the machine->model back-transform for the upright
+    // ("designed") belt preview.
+    const Transform3d& transform() const { return m_transform; }
+
+private:
+    bool        m_active            = false;
+    Transform3d m_transform         = Transform3d::Identity();
+    Transform3d m_transform_inverse = Transform3d::Identity();
+};
+
+} // namespace Slic3r
+
+#endif // slic3r_MachineFrameTransform_hpp_
@@ -0,0 +1,47 @@
+#include "MachineKinematics.hpp"
+
+namespace Slic3r {
+
+// Moved verbatim from GCodeWriter::apply_axis_remap().
+Vec3d CartesianKinematics::apply_axis_remap(const Vec3d &pos) const
+{
+    if (!has_axis_remap())
+        return pos;
+    auto remap = [this, &pos](int r) -> double {
+        int axis = r % 3;
+        if (r < 3) return pos[axis];
+        if (r < 6) return -pos[axis];
+        return m_build_vol_max[axis] - pos[axis];
+    };
+    return { remap(m_remap_x), remap(m_remap_y), remap(m_remap_z) };
+}
+
+// Inverse of the above.  Output axis i is fed by source axis (r_i % 3); walking
+// the three outputs therefore fills every source component exactly once, so long
+// as the remap is a permutation (which set_axis_remap callers guarantee).
+Vec3d CartesianKinematics::apply_axis_remap_inverse(const Vec3d &machine) const
+{
+    if (!has_axis_remap())
+        return machine;
+    Vec3d out = Vec3d::Zero();
+    const int r[3] = { m_remap_x, m_remap_y, m_remap_z };
+    for (int i = 0; i < 3; ++i) {
+        const int axis = r[i] % 3;
+        if (r[i] < 3)      out[axis] = machine[i];
+        else if (r[i] < 6) out[axis] = -machine[i];
+        else               out[axis] = m_build_vol_max[axis] - machine[i];
+    }
+    return out;
+}
+
+Vec3d CartesianKinematics::to_machine(const Vec3d &p) const
+{
+    return this->apply_axis_remap(p);
+}
+
+Vec3d CartesianKinematics::to_logical(const Vec3d &machine) const
+{
+    return this->apply_axis_remap_inverse(machine);
+}
+
+} // namespace Slic3r
@@ -0,0 +1,106 @@
+#ifndef slic3r_MachineKinematics_hpp_
+#define slic3r_MachineKinematics_hpp_
+
+#include "../Point.hpp"
+
+namespace Slic3r {
+
+// The frame contract for emitted movement.
+//
+// GCodeWriter produces points in the *logical placed* frame: plate offsets have
+// already been subtracted, but no machine-specific mapping has been applied.
+// A MachineKinematics turns that into the coordinates actually written to
+// G-code, and answers the two structural questions the writer needs in order to
+// decide which axis words it may omit.
+//
+// This is a seam for writer-generated movement only.  Start/end/custom G-code,
+// classic wipe-tower output and GCodeWriter::extrude_arc_to_xy() do NOT pass
+// through it: they write machine coordinates directly.
+class MachineKinematics
+{
+public:
+    virtual ~MachineKinematics() = default;
+
+    // Logical placed point -> emitted machine point.
+    virtual Vec3d to_machine(const Vec3d &p) const = 0;
+
+    // Inverse of to_machine(), back to the logical placed frame.  Intended for
+    // consumers that must reconstruct model coordinates from emitted G-code
+    // (the G-code viewer's upright preview).
+    virtual Vec3d to_logical(const Vec3d &machine) const = 0;
+
+    // Machine point -> build-volume frame, for bounds validation only.  This is
+    // deliberately NOT to_logical(): the build-volume check wants the physical
+    // frame the printable area is expressed in, not the model frame.  Keeping
+    // them separate stops the two contracts from being confused.
+    virtual Vec3d to_build_volume(const Vec3d &machine) const = 0;
+
+    // True when a move must emit X, Y and Z because omitting a word would be
+    // wrong under this mapping.  Deliberately not called "couples_axes": a pure
+    // axis permutation forces full emission without physically coupling axes.
+    virtual bool must_emit_all_axes() const = 0;
+
+    // True when a lift must be suppressed while the current position is unknown,
+    // because _travel_to_z() re-emits the logical X/Y through this mapping and an
+    // uninitialised position would map to a bogus machine point -- for a reverse
+    // mapping, the far corner of the bed.
+    virtual bool suppress_lift_at_unknown_position() const = 0;
+
+    // True when a G2/G3 arc in the logical XY plane is still the same arc in the
+    // machine frame. Arc moves emit only X, Y, I and J, so this asks a narrower
+    // question than must_emit_all_axes(): whether logical X and Y reach the
+    // machine unchanged. A mapping that only negates or reverses Z keeps its
+    // arcs; one that permutes X or Y moves the arc out of the plane that I/J
+    // describes, and a shear turns the circle into an ellipse G2/G3 cannot
+    // express at all.
+    virtual bool supports_arc_moves() const = 0;
+
+    // Configuration.  GCodeWriter forwards its setters here so that the state
+    // lives with the strategy and a strategy installed before the setters run
+    // still receives it.
+    virtual void set_axis_remap(int rx, int ry, int rz) = 0;
+    virtual void set_build_volume_max(const Vec3d &max) = 0;
+};
+
+// Axis remap only -- the historical GCodeWriter behaviour, moved verbatim.
+//
+// The remap encodes, per output axis, which source axis feeds it and how:
+//   r < 3 : source axis r, unchanged
+//   r < 6 : source axis r-3, negated
+//   else  : source axis r-6, reversed within the build volume
+class CartesianKinematics : public MachineKinematics
+{
+public:
+    Vec3d to_machine(const Vec3d &p) const override;
+    Vec3d to_logical(const Vec3d &machine) const override;
+    Vec3d to_build_volume(const Vec3d &machine) const override { return machine; }
+
+    bool must_emit_all_axes() const override { return this->has_axis_remap(); }
+    bool suppress_lift_at_unknown_position() const override { return this->has_axis_remap(); }
+
+    // X and Y must reach the machine untouched. Because the remap is a
+    // permutation, pinning those two also pins Z to Z, so a mapping that only
+    // negates or reverses Z still supports arcs -- every word a G2/G3 emits is
+    // unchanged by it.
+    bool supports_arc_moves() const override { return m_remap_x == 0 && m_remap_y == 1; }
+
+    void set_axis_remap(int rx, int ry, int rz) override
+        { m_remap_x = rx; m_remap_y = ry; m_remap_z = rz; }
+    void set_build_volume_max(const Vec3d &max) override { m_build_vol_max = max; }
+
+    bool has_axis_remap() const
+        { return m_remap_x != 0 || m_remap_y != 1 || m_remap_z != 2; }
+
+protected:
+    Vec3d apply_axis_remap(const Vec3d &pos) const;
+    Vec3d apply_axis_remap_inverse(const Vec3d &pos) const;
+
+    int   m_remap_x { 0 };
+    int   m_remap_y { 1 };
+    int   m_remap_z { 2 };
+    Vec3d m_build_vol_max { Vec3d::Zero() };
+};
+
+} // namespace Slic3r
+
+#endif // slic3r_MachineKinematics_hpp_
@@ -627,7 +627,7 @@ void compute_global_occlusion(GlobalModelInfo &result, const PrintObject *po,
                              SeamPosition seam_position = spAligned) {
  BOOST_LOG_TRIVIAL(debug)
      << "SeamPlacer: gather occlusion meshes: start";
-  auto obj_transform = po->trafo_centered();
+  auto obj_transform = po->trafo_sliced();
  indexed_triangle_set triangle_set;
  indexed_triangle_set negative_volumes_set;
  //add all parts
@@ -712,7 +712,7 @@ void gather_enforcers_blockers(GlobalModelInfo &result, const PrintObject *po) {
  BOOST_LOG_TRIVIAL(debug)
      << "SeamPlacer: build AABB trees for raycasting enforcers/blockers: start";

-  auto obj_transform = po->trafo_centered();
+  auto obj_transform = po->trafo_sliced();

  for (const ModelVolume *mv : po->model_object()->volumes) {
    if (mv->is_seam_painted()) {
@@ -395,6 +395,10 @@ bool ToolOrdering::insert_wipe_tower_extruder()
 {
    if (!m_print_config_ptr || !m_print_config_ptr->enable_prime_tower)
        return false;
+    // Belt mode has no classic wipe tower; the dedicated wipe tower filament
+    // must not inject extra toolchanges into the purge prism planning.
+    if (m_print_config_ptr->belt_printer)
+        return false;
    if (m_print_config_ptr->wipe_tower_filament == 0)
        return false;

@@ -492,6 +496,11 @@ ToolOrdering::ToolOrdering(const PrintObject &object, unsigned int first_extrude
            zs.emplace_back(layer->print_z);
        for (auto layer : object.support_layers())
            zs.emplace_back(layer->print_z);
+        // Belt brim apron bands sit below the object's first layer and have no
+        // layer of their own, but tools_for_layer() asserts an exact Z match, so
+        // their print_z must be part of the ordering.
+        for (const BeltBrimBand &band : object.belt_brim_prologue())
+            zs.emplace_back(band.print_z);
        this->initialize_layers(zs);
    }

@@ -536,6 +545,10 @@ ToolOrdering::ToolOrdering(const Print &print, unsigned int first_extruder, bool
                zs.emplace_back(layer->print_z);
            for (auto layer : object->support_layers())
                zs.emplace_back(layer->print_z);
+            // See the single-object ctor: belt brim apron bands need their own
+            // ordering entries or tools_for_layer() will assert.
+            for (const BeltBrimBand &band : object->belt_brim_prologue())
+                zs.emplace_back(band.print_z);

            max_layer_height = std::max(max_layer_height, object->config().layer_height.value);
        }
@@ -970,6 +983,44 @@ void ToolOrdering::collect_extruders(const PrintObject &object, const std::vecto
        }
    }

+    // Belt brim apron bands own their layers outright: they print below the
+    // object's first layer, so no object or support layer claims an extruder there
+    // and process_layer() would bail out at "Nothing to extrude".  Claim the
+    // object's outer wall filament, in the same raw 1-based domain the loops above
+    // push.  Deliberately not layer_tools.has_object, which drives skirt marking
+    // and wiping overrides.
+    if (! object.belt_brim_prologue().empty()) {
+        // 1-based, same domain the object/support pushes above use; reindexed to 0-based
+        // with the rest of the list later.
+        const unsigned int brim_filament = object.belt_brim_filament();
+        for (const BeltBrimBand &band : object.belt_brim_prologue()) {
+            if (band.fills.empty())
+                continue;
+            LayerTools &layer_tools = this->tools_for_layer(band.print_z);
+            layer_tools.extruders.push_back(brim_filament);
+            layer_tools.has_belt_brim = true;
+        }
+    }
+
+    // Coincident brim bands (belt_brim_by_layer) print ON an object layer rather than
+    // below it, but that layer can produce no InstanceVisit in process_layer - a
+    // zero-extrusion lead-in slice with no coinciding support - and the band would then
+    // be silently dropped.  Register the brim filament on every layer that carries a
+    // coincident band, in the same 1-based domain as the prologue push above, so a brim
+    // pass always exists there.
+    if (object.has_belt_brim()) {
+        const unsigned int brim_filament = object.belt_brim_filament();
+        const auto        &by_layer      = object.belt_brim_by_layer();
+        const size_t       n             = std::min(by_layer.size(), object.layers().size());
+        for (size_t i = 0; i < n; ++ i) {
+            if (by_layer[i].empty())
+                continue;
+            LayerTools &layer_tools = this->tools_for_layer(object.layers()[i]->print_z);
+            layer_tools.extruders.push_back(brim_filament);
+            layer_tools.has_belt_brim = true;
+        }
+    }
+
    for (auto& layer : m_layer_tools) {
        // Sort and remove duplicates
        sort_remove_duplicates(layer.extruders);
@@ -1012,12 +1063,28 @@ void ToolOrdering::fill_wipe_tower_partitions(const PrintConfig &config, coordf_
    }

    //FIXME this is a hack to get the ball rolling.
+    // The `print_z < object_bottom_z` clause reads "below the object" as "raft
+    // gap".  On a belt printer that is wrong: the brim apron legitimately prints
+    // below the object's first layer, and treating those layers as raft would put a
+    // wipe tower at negative Z.  A belt printer never prints the classic
+    // prime tower (Print::has_wipe_tower()), so simply drop the clause there.
+    //
+    // Gate on config.belt_printer, NOT on has_belt_brim: every layer below the
+    // object bottom on a belt printer is legitimately a sub-object stream - brim
+    // apron, belt support printed below Z0, or the object's own lead-in - and none of
+    // them is ever raft, because Print::validate() rejects raft_layers>0 on a belt
+    // printer outright.  Narrowing this to has_belt_brim would reclassify
+    // belt-support-below-floor layers as raft on brim-less belt prints and reintroduce
+    // the negative-Z wipe tower, so the broad belt_printer gate is correct.
+    const bool belt_no_raft_gap = config.belt_printer.value;
    for (LayerTools &lt : m_layer_tools)
        lt.has_wipe_tower |= ((lt.has_object || lt.has_support) && (config.timelapse_type == TimelapseType::tlSmooth || lt.wipe_tower_partitions > 0))
-            || lt.print_z < object_bottom_z + EPSILON;
+            || (! belt_no_raft_gap && lt.print_z < object_bottom_z + EPSILON);

    // Test for a raft, insert additional wipe tower layer to fill in the raft separation gap.
-    for (size_t i = 0; i + 1 < m_layer_tools.size(); ++ i) {
+    // Skipped on belt printers for the same reason as the clause above: layers
+    // below the object are brim apron, not raft.
+    for (size_t i = 0; ! belt_no_raft_gap && i + 1 < m_layer_tools.size(); ++ i) {
        const LayerTools &lt      = m_layer_tools[i];
        const LayerTools &lt_next = m_layer_tools[i + 1];
        if (lt.print_z < object_bottom_z + EPSILON && lt_next.print_z >= object_bottom_z + EPSILON) {
@@ -74,7 +74,17 @@ public:

    void set_layer_tools_ptr(const LayerTools* lt) { m_layer_tools = lt; }

+    // Returns true if entity is not printed with its usual extruder for a given
+    // copy -- i.e. it was claimed as a wiping/purge extrusion. Public because the
+    // belt purge prism uses it to tell which of its fills actually carry purge
+    // from the ones that are unclaimed waste (Print::_plan_belt_purge()).
+    bool is_entity_overridden(const ExtrusionEntity* entity, const PrintObject *object, size_t copy_id) const {
+        auto it = entity_map.find(std::make_tuple(entity, object));
+        return it != entity_map.end() && copy_id < it->second.size() && it->second[copy_id] != -1;
+    }
+
 private:
+
    int first_nonsoluble_extruder_on_layer(const PrintConfig& print_config) const;
    int last_nonsoluble_extruder_on_layer(const PrintConfig& print_config) const;

@@ -84,12 +94,6 @@ private:
    void set_support_extruder_override(const PrintObject* object, size_t copy_id, int extruder, size_t num_of_copies);
    void set_support_interface_extruder_override(const PrintObject* object, size_t copy_id, int extruder, size_t num_of_copies);

-    // Returns true in case that entity is not printed with its usual extruder for a given copy:
-    bool is_entity_overridden(const ExtrusionEntity* entity, const PrintObject *object, size_t copy_id) const {
-        auto it = entity_map.find(std::make_tuple(entity, object));
-        return it == entity_map.end() ? false : it->second[copy_id] != -1;
-    }
-
    std::map<std::tuple<const ExtrusionEntity*, const PrintObject *>, ExtruderPerCopy> entity_map;  // to keep track of who prints what
    // BBS
    std::map<const PrintObject*, int> support_map;
@@ -165,6 +169,10 @@ public:
    // Should a skirt be printed at this layer?
    // Layers are marked for infinite skirt aka draft shield. Not all the layers have to be printed.
    bool                        has_skirt = false;
+    // Belt printers: is this one of the brim-only apron layers below the object's
+    // first layer?  Kept separate from has_object so skirt marking and wiping
+    // overrides are unaffected.
+    bool                        has_belt_brim = false;
    // Will there be anything extruded on this layer for the wipe tower?
    // Due to the support layers possibly interleaving the object layers,
    // wipe tower will be disabled for some support only layers.
@@ -1,5 +1,7 @@
 #include "GCodeWriter.hpp"
+#include "FirstLayerPlane.hpp"
 #include "CustomGCode.hpp"
+#include "Geometry.hpp"
 #include "I18N.hpp"
 #include "PrintConfig.hpp"
 #include "ClipperUtils.hpp"
@@ -23,6 +25,57 @@ namespace Slic3r {

 bool GCodeWriter::full_gcode_comment = true;

+// A lift emitted through _travel_to_z() re-emits the stored logical X/Y under a
+// mapping that must emit every axis. While the position is unknown that X/Y is
+// the uninitialised origin, which maps to a real but wrong machine point, so the
+// lift has to be skipped rather than commanded.
+bool GCodeWriter::must_skip_lift_now() const
+{
+    return m_kinematics->suppress_lift_at_unknown_position() && ! this->is_current_position_clear();
+}
+
+bool GCodeWriter::point_on_first_layer(const Vec3d &point_logical) const
+{
+    if (m_first_layer_plane && m_first_layer_plane->is_active())
+        return m_first_layer_plane->is_first_layer(point_logical, m_first_layer_thickness_mm);
+    return m_is_first_layer;
+}
+
+void GCodeWriter::set_axis_remap(int rx, int ry, int rz)
+{
+    m_remap_x = rx;
+    m_remap_y = ry;
+    m_remap_z = rz;
+    m_kinematics->set_axis_remap(rx, ry, rz);
+}
+
+void GCodeWriter::set_build_volume_max(const Vec3d &max)
+{
+    m_build_vol_max = max;
+    m_kinematics->set_build_volume_max(max);
+}
+
+void GCodeWriter::set_kinematics(std::unique_ptr<MachineKinematics> kinematics)
+{
+    assert(kinematics);
+    m_kinematics = std::move(kinematics);
+    // Replay whatever was configured on the previous strategy so callers may
+    // install the kinematics before or after set_axis_remap/set_build_volume_max.
+    m_kinematics->set_axis_remap(m_remap_x, m_remap_y, m_remap_z);
+    m_kinematics->set_build_volume_max(m_build_vol_max);
+}
+
+// Kept as the writer-facing name for "this move must emit every axis word".
+bool GCodeWriter::has_axis_remap() const
+{
+    return m_kinematics->must_emit_all_axes();
+}
+
+Vec3d GCodeWriter::apply_axis_remap(const Vec3d &pos) const
+{
+    return m_kinematics->to_machine(pos);
+}
+
 bool GCodeWriter::supports_separate_travel_acceleration(GCodeFlavor flavor)
 {
    return (flavor == gcfRepetier || flavor == gcfMarlinFirmware ||  flavor == gcfRepRapFirmware);
@@ -757,8 +810,14 @@ std::string GCodeWriter::travel_to_xy(const Vec2d &point, const std::string &com
    Vec2d point_on_plate = { point(0) - m_x_offset, point(1) - m_y_offset };

    GCodeG1Formatter w;
-    w.emit_xy(point_on_plate);
-    auto speed = m_is_first_layer
+    if (has_axis_remap()) {
+        // Axis remap may couple XY with Z; emit full XYZ in machine coordinates.
+        Vec3d machine = apply_axis_remap(Vec3d(point_on_plate.x(), point_on_plate.y(), m_pos.z()));
+        w.emit_xyz(machine);
+    } else {
+        w.emit_xy(point_on_plate);
+    }
+    auto speed = this->point_on_first_layer(Vec3d(point_on_plate.x(), point_on_plate.y(), m_pos.z()))
        ? this->config.get_abs_value_at("initial_layer_travel_speed", m_cached_extruder_idx) : this->config.travel_speed.get_at(m_cached_extruder_idx);
    w.emit_f(speed * 60.0);
    //BBS
@@ -771,6 +830,8 @@ it will not perform subsequent lifts, even if Z was raised manually
 (i.e. with travel_to_z()) and thus _lifted was reduced. */
 std::string GCodeWriter::lazy_lift(LiftType lift_type, bool spiral_vase)
 {
+    if (m_force_normal_lift)
+        lift_type = LiftType::NormalLift;
    // check whether the above/below conditions are met
    double target_lift = 0;
    {
@@ -785,6 +846,10 @@ std::string GCodeWriter::lazy_lift(LiftType lift_type, bool spiral_vase)
    // BBS
    if (m_lifted == 0 && m_to_lift == 0 && target_lift > 0) {
        if (spiral_vase) {
+            if (this->must_skip_lift_now())
+                // Record no lift, so a later unlift() does not descend from a
+                // height that was never commanded.
+                return "";
            m_lifted = target_lift;
            return this->_travel_to_z(m_pos(2) + target_lift, "lift Z");
        }
@@ -797,8 +862,9 @@ std::string GCodeWriter::lazy_lift(LiftType lift_type, bool spiral_vase)
 }

 // BBS: immediately execute an undelayed lift move with a spiral lift pattern
-// designed specifically for subsequent gcode injection (e.g. timelapse) 
+// designed specifically for subsequent gcode injection (e.g. timelapse)
 std::string GCodeWriter::eager_lift(const LiftType type) {
+    const LiftType effective_type = m_force_normal_lift ? LiftType::NormalLift : type;
    std::string lift_move;
    double target_lift = 0;
    {
@@ -812,7 +878,7 @@ std::string GCodeWriter::eager_lift(const LiftType type) {
    }

    // BBS: spiral lift only safe with known position
-    if (type == LiftType::SpiralLift && this->is_current_position_clear()) {
+    if (effective_type == LiftType::SpiralLift && this->is_current_position_clear()) {
        double radius = target_lift / (2 * PI * atan(filament()->travel_slope()));
        // static spiral alignment when no move in x,y plane.
        // spiral centra is a radius distance to the right (y=0)
@@ -829,7 +895,12 @@ std::string GCodeWriter::eager_lift(const LiftType type) {
    }
    //BBS: if position is unknown use normal lift
    else if (target_lift > 0) {
-        lift_move = _travel_to_z(m_pos(2) + target_lift, "normal lift Z");
+        if (this->must_skip_lift_now())
+            // Skipped, not deferred: leave m_lifted at zero below so unlift()
+            // does not descend from a height that was never commanded.
+            target_lift = 0.;
+        else
+            lift_move = _travel_to_z(m_pos(2) + target_lift, "normal lift Z");
    }
    m_lifted = target_lift;
    m_to_lift = 0;
@@ -850,7 +921,12 @@ std::string GCodeWriter::travel_to_xyz(const Vec3d &point, const std::string &co
        // BBS
    Vec3d dest_point = point;
    auto travel_speed =
-        m_is_first_layer ? this->config.get_abs_value_at("initial_layer_travel_speed", m_cached_extruder_idx) : this->config.travel_speed.get_at(m_cached_extruder_idx);
+        this->point_on_first_layer(Vec3d(point.x() - m_x_offset, point.y() - m_y_offset, point.z())) ? this->config.get_abs_value_at("initial_layer_travel_speed", m_cached_extruder_idx) : this->config.travel_speed.get_at(m_cached_extruder_idx);
+    // See uses_pointwise_travel_speed(): the historical path deliberately emits the
+    // raw configured speed in the final branch below, ignoring travel_speed.
+    const double final_travel_speed = this->uses_pointwise_travel_speed()
+        ? travel_speed
+        : this->config.travel_speed.get_at(m_cached_extruder_idx);
    //BBS: a z_hop need to be handle when travel
    if (std::abs(m_to_lift) > EPSILON) {
        assert(std::abs(m_lifted) < EPSILON);
@@ -899,13 +975,23 @@ std::string GCodeWriter::travel_to_xyz(const Vec3d &point, const std::string &co
                Vec2d temp = delta_no_z.normalized() * delta(2) / tan(this->filament()->travel_slope());
                Vec3d slope_top_point = Vec3d(temp(0), temp(1), delta(2)) + source;
                GCodeG1Formatter w0;
-                w0.emit_xyz(slope_top_point);
+                // A slope lift is a straight (linear) diagonal move, so remapping its
+                // endpoint is exact. Route the destination through apply_axis_remap()
+                // when a remap is active (no-op at identity).
+                w0.emit_xyz(has_axis_remap() ? apply_axis_remap(slope_top_point) : slope_top_point);
                w0.emit_f(travel_speed * 60.0);
                //BBS
                w0.emit_comment(GCodeWriter::full_gcode_comment, comment);
                slop_move = w0.string();
            }
-            else if (m_to_lift_type == LiftType::NormalLift) {
+            else if (m_to_lift_type == LiftType::NormalLift && ! this->must_skip_lift_now()) {
+                // Only lift in place when the current position is known, for a mapping
+                // that makes _travel_to_z re-emit logical X/Y: at print start (and after
+                // custom gcode) m_pos.xy is still the uninitialised origin, which would
+                // map to a bogus machine point. The xy_z_move below then travels straight
+                // to the destination with full XYZ and establishes the correct position.
+                // Mappings that do not need this (the historical Cartesian behaviour)
+                // report false and keep lifting unconditionally.
                slop_move = _travel_to_z(target.z(), "normal lift Z");
            }
        }
@@ -913,7 +999,14 @@ std::string GCodeWriter::travel_to_xyz(const Vec3d &point, const std::string &co
        std::string xy_z_move;
        {
            GCodeG1Formatter w0;
-            if (this->is_current_position_clear()) {
+            if (has_axis_remap()) {
+                // Remap may couple XY with Z; emit full XYZ in machine coordinates.
+                w0.emit_xyz(apply_axis_remap(target));
+                w0.emit_f(travel_speed * 60.0);
+                w0.emit_comment(GCodeWriter::full_gcode_comment, comment);
+                xy_z_move = w0.string();
+            }
+            else if (this->is_current_position_clear()) {
                w0.emit_xyz(target);
                w0.emit_f(travel_speed * 60.0);
                w0.emit_comment(GCodeWriter::full_gcode_comment, comment);
@@ -951,17 +1044,23 @@ std::string GCodeWriter::travel_to_xyz(const Vec3d &point, const std::string &co
    Vec3d point_on_plate = { dest_point(0) - m_x_offset, dest_point(1) - m_y_offset, dest_point(2) };
    std::string out_string;
    GCodeG1Formatter w;
-    if (!this->is_current_position_clear())
+    if (has_axis_remap()) {
+        // Remap may couple XY with Z; emit full XYZ in machine coordinates.
+        w.emit_xyz(apply_axis_remap(point_on_plate));
+        w.emit_f(final_travel_speed * 60.0);
+        w.emit_comment(GCodeWriter::full_gcode_comment, comment);
+        out_string = w.string();
+    } else if (!this->is_current_position_clear())
    {
        //force to move xy first then z after filament change
        w.emit_xy(Vec2d(point_on_plate.x(), point_on_plate.y()));
-        w.emit_f(this->config.travel_speed.get_at(m_cached_extruder_idx) * 60.0);
+        w.emit_f(final_travel_speed * 60.0);
        w.emit_comment(GCodeWriter::full_gcode_comment, comment);
        out_string = w.string() + _travel_to_z(point_on_plate.z(), comment);
    } else {
        GCodeG1Formatter w;
        w.emit_xyz(point_on_plate);
-        w.emit_f(this->config.travel_speed.get_at(m_cached_extruder_idx) * 60.0);
+        w.emit_f(final_travel_speed * 60.0);
        w.emit_comment(GCodeWriter::full_gcode_comment, comment);
        out_string = w.string();
    }
@@ -996,12 +1095,19 @@ std::string GCodeWriter::_travel_to_z(double z, const std::string &comment)

    double speed = this->config.travel_speed_z.get_at(m_cached_extruder_idx);
    if (speed == 0.) {
-        speed = m_is_first_layer ? this->config.get_abs_value_at("initial_layer_travel_speed", m_cached_extruder_idx)
-                                 : this->config.travel_speed.get_at(m_cached_extruder_idx);
+        speed = this->point_on_first_layer(Vec3d(m_pos.x() - m_x_offset, m_pos.y() - m_y_offset, z))
+                    ? this->config.get_abs_value_at("initial_layer_travel_speed", m_cached_extruder_idx)
+                    : this->config.travel_speed.get_at(m_cached_extruder_idx);
    }

    GCodeG1Formatter w;
-    w.emit_z(z);
+    if (has_axis_remap()) {
+        // Remap may couple Z with other axes; emit full XYZ.
+        Vec3d machine = apply_axis_remap(Vec3d(m_pos.x() - m_x_offset, m_pos.y() - m_y_offset, z));
+        w.emit_xyz(machine);
+    } else {
+        w.emit_z(z);
+    }
    w.emit_f(speed * 60.0);
    //BBS
    w.emit_comment(GCodeWriter::full_gcode_comment, comment);
@@ -1010,6 +1116,14 @@ std::string GCodeWriter::_travel_to_z(double z, const std::string &comment)

 std::string GCodeWriter::_spiral_travel_to_z(double z, const Vec2d &ij_offset, const std::string &comment)
 {
+    // A circular XY arc / spiral lift cannot be correctly axis-remapped by
+    // transforming only its endpoint: the arc plane (G17/XY) and the I-J center
+    // would change under the remap. When an axis remap is active, fall back to a
+    // plain linear lift instead of emitting a possibly-wrong spiral/arc. This
+    // single guard covers every spiral call site (lazy/eager lift and travel_to_xyz).
+    if (has_axis_remap())
+        return _travel_to_z(z, comment);
+
    std::string output;
    double speed = this->config.travel_speed_z.get_at(m_cached_extruder_idx);

@@ -1109,7 +1223,12 @@ std::string GCodeWriter::extrude_to_xy(const Vec2d &point, double dE, const std:
    Vec2d point_on_plate = { point(0) - m_x_offset, point(1) - m_y_offset };

    GCodeG1Formatter w;
-    w.emit_xy(point_on_plate);
+    if (has_axis_remap()) {
+        Vec3d machine = apply_axis_remap(Vec3d(point_on_plate.x(), point_on_plate.y(), m_pos.z()));
+        w.emit_xyz(machine);
+    } else {
+        w.emit_xy(point_on_plate);
+    }
    if (!force_no_extrusion)
        w.emit_e(filament()->E());
    //BBS
@@ -1117,11 +1236,62 @@ std::string GCodeWriter::extrude_to_xy(const Vec2d &point, double dE, const std:
    return w.string();
 }

+// Approximate an arc with linear extrusions, for machine mappings that cannot
+// express a G2/G3 (see extrude_arc_to_xy). center_offset is I/J: the centre
+// relative to the CURRENT position, which is why this must run before m_pos is
+// updated.
+std::string GCodeWriter::extrude_arc_as_polyline(const Vec2d &point, const Vec2d &center_offset,
+                                                 double dE, const bool is_ccw,
+                                                 const std::string &comment, bool force_no_extrusion)
+{
+    const Vec2d start  = Vec2d(m_pos.x(), m_pos.y());
+    const Vec2d centre = start + center_offset;
+    const double r     = (start - centre).norm();
+    if (r < EPSILON)
+        // Degenerate: no arc to speak of, so a single move is exact.
+        return this->extrude_to_xy(point, dE, comment, force_no_extrusion);
+
+    double a0 = std::atan2(start.y() - centre.y(), start.x() - centre.x());
+    double a1 = std::atan2(point.y() - centre.y(), point.x() - centre.x());
+    double sweep = a1 - a0;
+    if (is_ccw) { while (sweep <= 0.) sweep += 2. * PI; }
+    else        { while (sweep >= 0.) sweep -= 2. * PI; }
+
+    // Segment count from a chord-deviation bound: r*(1-cos(dtheta/2)) <= tol.
+    const double tol  = 0.005;                       // mm
+    const double dmax = (tol >= r) ? PI : 2. * std::acos(1. - tol / r);
+    const int    n    = std::max(2, int(std::ceil(std::abs(sweep) / std::max(dmax, EPSILON))));
+
+    std::string out;
+    for (int i = 1; i <= n; ++ i) {
+        const double a = a0 + sweep * (double(i) / double(n));
+        const Vec2d  p = (i == n) ? point
+                                  : Vec2d(centre.x() + r * std::cos(a), centre.y() + r * std::sin(a));
+        out += this->extrude_to_xy(p, dE / double(n), i == n ? comment : std::string(), force_no_extrusion);
+    }
+    return out;
+}
+
 //BBS: generate G2 or G3 extrude which moves by arc
 //point is end point which means X and Y axis
 //center_offset is I and J axis
 std::string GCodeWriter::extrude_arc_to_xy(const Vec2d& point, const Vec2d& center_offset, double dE, const bool is_ccw, const std::string& comment, bool force_no_extrusion)
 {
+    // Arcs emit only X/Y/I/J, so a mapping that moves logical X or Y cannot be
+    // expressed as a G2/G3. GCode::should_disable_arc_fitting() normally stops
+    // arcs being generated at all for such a mapping, but this is public API, so
+    // define the behaviour rather than asserting.
+    //
+    // This check MUST precede every state mutation below: falling through to
+    // extrude_to_xy() after filament()->extrude(dE) would advance E twice.
+    //
+    // A single chord is not a safe substitute either -- a semicircle would become
+    // its diameter and a full circle a stationary blob -- so approximate the arc
+    // with linear segments bounded by a chord tolerance, splitting dE between
+    // them in proportion to arc length.
+    if (! m_kinematics->supports_arc_moves())
+        return this->extrude_arc_as_polyline(point, center_offset, dE, is_ccw, comment, force_no_extrusion);
+
    m_pos(0) = point(0);
    m_pos(1) = point(1);
    if (!force_no_extrusion)
@@ -1155,10 +1325,18 @@ std::string GCodeWriter::extrude_to_xyz(const Vec3d &point, double dE, const std
    Vec3d point_on_plate = { point(0) - m_x_offset, point(1) - m_y_offset, point(2) };

    GCodeG1Formatter w;
-    if (z_changed)
+    if (has_axis_remap()) {
+        // z_changed was computed from the ORIGINAL slicing Z, but an axis remap can
+        // make machine-Z depend on slicing X/Y. An X/Y-only move (slicing-Z
+        // unchanged) would then drop the required machine-Z word, so always emit
+        // full XYZ whenever a remap is active.
+        point_on_plate = apply_axis_remap(point_on_plate);
        w.emit_xyz(point_on_plate);
-    else
+    } else if (z_changed) {
+        w.emit_xyz(point_on_plate);
+    } else {
        w.emit_xy(Vec2d(point_on_plate.x(), point_on_plate.y()));
+    }
    if (!force_no_extrusion)
        w.emit_e(filament()->E());
    //BBS
@@ -9,26 +9,32 @@
 #include "Polygon.hpp"
 #include "PrintConfig.hpp"
 #include "GCode/CoolingBuffer.hpp"
-
+#include "GCode/MachineKinematics.hpp"
+#include <memory>
 namespace Slic3r {

+class FirstLayerPlane;
+
 class GCodeWriter {
 public:
+    virtual ~GCodeWriter() = default;
    GCodeConfig config;
    bool multiple_extruders;

    GCodeWriter() :
-        multiple_extruders(false), m_curr_filament_extruder(MAXIMUM_EXTRUDER_NUMBER, nullptr),
-        m_curr_extruder_id (-1),
-        m_cached_extruder_idx(0),
-        m_single_extruder_multi_material(false),
-        m_last_acceleration(0), m_max_acceleration(0),m_last_travel_acceleration(0), m_max_travel_acceleration(0),
-        m_last_jerk(0), m_max_jerk_x(0), m_max_jerk_y(0),
-        m_last_bed_temperature(0), m_last_bed_temperature_reached(true),
+        multiple_extruders(false),
        m_lifted(0),
        m_to_lift(0),
        m_to_lift_type(LiftType::NormalLift),
-        m_current_speed(3600), m_is_first_layer(true)
+        m_is_first_layer(true), m_current_speed(3600),
+        m_kinematics(std::make_unique<CartesianKinematics>()),
+        m_cached_extruder_idx(0),
+        m_curr_filament_extruder(MAXIMUM_EXTRUDER_NUMBER, nullptr),
+        m_curr_extruder_id (-1),
+        m_single_extruder_multi_material(false),
+        m_last_acceleration(0), m_max_acceleration(0),m_last_travel_acceleration(0), m_max_travel_acceleration(0),
+        m_last_jerk(0), m_max_jerk_x(0), m_max_jerk_y(0),
+        m_last_bed_temperature(0), m_last_bed_temperature_reached(true)
        {}
    Extruder* filament(size_t extruder_id) { assert(extruder_id < m_curr_filament_extruder.size()); return m_curr_filament_extruder[extruder_id]; }
    const Extruder* filament(size_t extruder_id) const { assert(extruder_id < m_curr_filament_extruder.size()); return m_curr_filament_extruder[extruder_id]; }
@@ -78,23 +84,27 @@ public:
    std::string set_speed(double F, const std::string &comment = std::string(), const std::string &cooling_marker = std::string());
    // SoftFever NOTE: the returned speed is mm/minute
    double      get_current_speed() const { return m_current_speed;}
-    std::string travel_to_xy(const Vec2d &point, const std::string &comment = std::string());
-    std::string travel_to_xyz(const Vec3d &point, const std::string &comment = std::string(), bool force_z = false);
+    virtual std::string travel_to_xy(const Vec2d &point, const std::string &comment = std::string());
+    virtual std::string travel_to_xyz(const Vec3d &point, const std::string &comment = std::string(), bool force_z = false);
    std::string travel_to_z(double z, const std::string &comment = std::string(), bool force = false);
    bool        will_move_z(double z) const;
-    std::string extrude_to_xy(const Vec2d &point, double dE, const std::string &comment = std::string(), bool force_no_extrusion = false);
+    virtual std::string extrude_to_xy(const Vec2d &point, double dE, const std::string &comment = std::string(), bool force_no_extrusion = false);
    //BBS: generate G2 or G3 extrude which moves by arc
    std::string extrude_arc_to_xy(const Vec2d &point, const Vec2d &center_offset, double dE, const bool is_ccw, const std::string &comment = std::string(), bool force_no_extrusion = false);
-    std::string extrude_to_xyz(const Vec3d &point, double dE, const std::string &comment = std::string(), bool force_no_extrusion = false);
+    // Linear approximation of an arc, used when the machine mapping cannot
+    // express a G2/G3. Must be called before m_pos is updated: center_offset is
+    // relative to the current position.
+    std::string extrude_arc_as_polyline(const Vec2d &point, const Vec2d &center_offset, double dE, const bool is_ccw, const std::string &comment = std::string(), bool force_no_extrusion = false);
+    virtual std::string extrude_to_xyz(const Vec3d &point, double dE, const std::string &comment = std::string(), bool force_no_extrusion = false);
    std::string retract(bool before_wipe = false, double retract_length = 0);
    std::string retract_for_toolchange(bool before_wipe = false, double retract_length = 0);
    // extra_retract adds a small over-extrusion to the deretract move (PETG pre-extrusion).
    // Default 0 -> byte-identical to the plain deretract.
    std::string unretract(float extra_retract = 0.f);
    // do lift instantly
-    std::string eager_lift(const LiftType type);
+    virtual std::string eager_lift(const LiftType type);
    // record a lift request, do realy lift in next travel
-    std::string lazy_lift(LiftType lift_type = LiftType::NormalLift, bool spiral_vase = false);
+    virtual std::string lazy_lift(LiftType lift_type = LiftType::NormalLift, bool spiral_vase = false);
    std::string unlift();
    const Vec3d& get_position() const { return m_pos; }
    Vec3d&       get_position() { return m_pos; }
@@ -136,16 +146,97 @@ public:
    void invalidate_acceleration() { m_last_acceleration = 0; m_last_travel_acceleration = 0; }
    void invalidate_jerk() { m_last_jerk = 0; }

+    // Axis remap: permute/negate/reverse axes in G-code output.
+    // Works standalone (without belt mode) for printers with non-standard axis conventions.
+    void set_axis_remap(int rx, int ry, int rz);
+    void set_build_volume_max(const Vec3d &max);
+    bool has_axis_remap() const;
+
+    // Install the machine frame mapping.  Any axis remap / build volume already
+    // configured is carried over, so install order does not matter.
+    void set_kinematics(std::unique_ptr<MachineKinematics> kinematics);
+    const MachineKinematics& kinematics() const { return *m_kinematics; }
+
+    // First-layer plane evaluator.  When set to an active plane, travel speed
+    // selection consults the plane per destination point instead of the
+    // layer-coarse m_is_first_layer flag.  Borrowed pointer; lifetime is owned
+    // by GCode, which constructs the plane after the writer exists -- so this is
+    // deliberately a setter and not a constructor argument.
+    void set_first_layer_plane(const FirstLayerPlane *plane, double first_layer_height_mm)
+        { m_first_layer_plane = plane; m_first_layer_thickness_mm = first_layer_height_mm; }
+
+    // Force every lift to a plain vertical lift.  Spiral and slope lifts compute
+    // their slope in the logical frame and do not account for a machine mapping
+    // that couples axes.
+    void set_force_normal_lift(bool force) { m_force_normal_lift = force; }
+
    // Returns whether this flavor supports separate print and travel acceleration.
    static bool supports_separate_travel_acceleration(GCodeFlavor flavor);
-  private:
+protected:
+    // Position/lift/offset state.
+    Vec3d           m_pos = Vec3d::Zero();
+    double          m_x_offset{ 0 };
+    double          m_y_offset{ 0 };
+    double          m_lifted;
+    double          m_to_lift;
+    LiftType        m_to_lift_type;
+    bool            m_is_first_layer = true;
+    bool            m_is_current_pos_clear = false;
+    double          m_current_speed;
+
+    virtual std::string _travel_to_z(double z, const std::string &comment);
+
+    // Whether a destination gets first-layer treatment.  With an active plane
+    // evaluator, distance from the plane decides; otherwise the layer-coarse
+    // m_is_first_layer flag does.
+    bool point_on_first_layer(const Vec3d &point_logical) const;
+
+    // True when a lift must be skipped because this mapping would emit the
+    // stored logical X/Y and that position is not yet known.
+    bool must_skip_lift_now() const;
+
+    // True when travel speed is selected per destination point rather than per
+    // layer. Set for writers that install a first-layer plane. The historical
+    // path emits the raw configured travel speed in the final branch of
+    // travel_to_xyz(), ignoring the first-layer selection computed at the top of
+    // that function; a plane-driven writer uses the first-layer-aware value
+    // throughout. Both are preserved exactly -- unifying them would change
+    // emitted feedrates and belongs in its own commit.
+    bool uses_pointwise_travel_speed() const { return m_first_layer_plane != nullptr; }
+
+    // Borrowed; null = inactive.
+    const FirstLayerPlane *m_first_layer_plane = nullptr;
+    double                 m_first_layer_thickness_mm = 0.;
+    bool                   m_force_normal_lift = false;
+
+    // The machine frame mapping.  Owns the axis-remap state that used to live
+    // here as m_remap_* / m_build_vol_max; the setters above forward to it.
+    // Never null: a CartesianKinematics at the identity remap reproduces the
+    // historical behaviour exactly.
+    std::unique_ptr<MachineKinematics> m_kinematics;
+
+    // Last configured remap / build volume, replayed onto a newly installed
+    // kinematics so set_kinematics() and the setters are order-independent.
+    int             m_remap_x = 0;  // RemapAxis: 0=+X, 1=+Y, 2=+Z, 3=-X, etc.
+    int             m_remap_y = 1;
+    int             m_remap_z = 2;
+    Vec3d           m_build_vol_max = Vec3d::Zero();
+
+    // Apply the machine frame mapping to a point. Returns pos unchanged when the
+    // mapping is the identity.
+    Vec3d apply_axis_remap(const Vec3d &pos) const;
+
+    // Motion uses the global/base process variant until a filament becomes active.
+    // Protected so subclasses index the per-extruder speed options (travel_speed,
+    // travel_speed_z, initial_layer_travel_speed) exactly as the base writer does.
+    size_t     m_cached_extruder_idx;
+
+private:
 	// Extruders are sorted by their ID, so that binary search is possible.
    std::vector<Extruder> m_filament_extruders;
    bool            m_single_extruder_multi_material;
    std::vector<Extruder*> m_curr_filament_extruder;
    int        m_curr_extruder_id;
-    // Motion uses the global/base process variant until a filament becomes active.
-    size_t     m_cached_extruder_idx;
    unsigned int              m_last_acceleration;
    unsigned int              m_last_travel_acceleration;
    std::vector<unsigned int> m_max_travel_acceleration;
@@ -167,19 +258,6 @@ public:
    //BBS
    int             m_last_bed_temperature;
    bool            m_last_bed_temperature_reached;
-    double          m_lifted;
-
-    // BBS
-    double          m_to_lift;
-    LiftType        m_to_lift_type;
-    Vec3d           m_pos = Vec3d::Zero();
-    //BBS: this flag is used to indicate whether the m_pos is real.
-    //A example that of the first move, the m_pos is zero, but the real position of extruder doesn't
-    //Pos must be clear after the first xyz travel move
-    bool            m_is_current_pos_clear = false;
-    //BBS: x, y offset for gcode generated
-    double          m_x_offset{ 0 };
-    double          m_y_offset{ 0 };

    // Orca: slicing resolution in mm
    double          m_resolution = 0.01;
@@ -191,21 +269,18 @@ public:
    // non-rectangular beds such as delta/circular printers.
    Polygon              m_bed_printable_area;
    std::vector<Polygon> m_extruder_printable_areas;
-    
+
    std::string m_gcode_label_objects_start;
    std::string m_gcode_label_objects_end;

    //SoftFever
    bool            m_is_bbl_printers = false;
-    double          m_current_speed;
-    bool            m_is_first_layer = true;

    enum class Acceleration {
        Travel,
        Print
    };

-    std::string _travel_to_z(double z, const std::string &comment);
    std::string _spiral_travel_to_z(double z, const Vec2d &ij_offset, const std::string &comment);
    // Orca: printable area of the active extruder (per-extruder when configured, otherwise the bed). Null when unknown.
    const Polygon *active_printable_area() const;
@@ -1215,7 +1215,7 @@ static inline std::vector<std::vector<ExPolygons>> segmentation_top_and_bottom_l
    // project downards pointing painted triangles over bottom surfaces.
    std::vector<std::vector<Polygons>> top_raw(num_facets_states), bottom_raw(num_facets_states);
    std::vector<float> zs = zs_from_layers(layers);
-    Transform3d        object_trafo = print_object.trafo_centered();
+    Transform3d        object_trafo = print_object.trafo_sliced();

 #ifdef MM_SEGMENTATION_DEBUG_TOP_BOTTOM
    static int iRun = 0;
@@ -1244,10 +1244,16 @@ static inline std::vector<std::vector<ExPolygons>> segmentation_top_and_bottom_l
                            slicing_params.trafo = volume_trafo;
                            Polygons bottom_slice = slice_mesh(painted, zs[0], slicing_params);

-                            top.erase(top.begin());
-                            bottom.erase(bottom.begin());
-
-                            bottom[0] = union_(bottom[0], bottom_slice);
+                            // Only the requested projections exist: with
+                            // top_shell_layers = 0 `top` is empty and erasing its begin() was
+                            // undefined (found by fuzzing: a sunk, painted object crashed here).
+                            if (! top.empty())
+                                top.erase(top.begin());
+                            if (! bottom.empty()) {
+                                bottom.erase(bottom.begin());
+                                if (! bottom.empty())
+                                    bottom[0] = union_(bottom[0], bottom_slice);
+                            }
                        } else
                            slice_mesh_slabs(painted, zs, volume_trafo, max_top_layers > 0 ? &top : nullptr, max_bottom_layers > 0 ? &bottom : nullptr, nullptr, throw_on_cancel_callback);
                        auto merge = [](std::vector<Polygons> &&src, std::vector<Polygons> &dst) {
@@ -2039,17 +2045,19 @@ std::vector<std::vector<ExPolygons>> segmentation_by_painting(const PrintObject
    }

    BOOST_LOG_TRIVIAL(debug) << "Print object segmentation - Projection of painted triangles - Begin";
+    // The layers were sliced in this frame (belt rotation, remap and Z lift included), and it already centers the object.
+    const Transform3d object_trafo = print_object.trafo_sliced();
    for (const ModelVolume *mv : print_object.model_object()->volumes) {
        const ModelVolumeFacetsInfo facets_info = extract_facets_info(*mv);
-        tbb::parallel_for(tbb::blocked_range<size_t>(1, num_facets_states), [&mv, &print_object, &facets_info, &layers, &edge_grids, &painted_lines, &painted_lines_mutex, &input_expolygons, &throw_on_cancel_callback](const tbb::blocked_range<size_t> &range) {
+        tbb::parallel_for(tbb::blocked_range<size_t>(1, num_facets_states), [&mv, &object_trafo, &facets_info, &layers, &edge_grids, &painted_lines, &painted_lines_mutex, &input_expolygons, &throw_on_cancel_callback](const tbb::blocked_range<size_t> &range) {
            for (size_t extruder_idx = range.begin(); extruder_idx < range.end(); ++extruder_idx) {
                throw_on_cancel_callback();
                const indexed_triangle_set custom_facets = facets_info.facets_annotation.get_facets(*mv, EnforcerBlockerType(extruder_idx));
                if (!mv->is_model_part() || custom_facets.indices.empty())
                    continue;

-                const Transform3f tr = print_object.trafo().cast<float>() * mv->get_matrix().cast<float>();
-                tbb::parallel_for(tbb::blocked_range<size_t>(0, custom_facets.indices.size()), [&tr, &custom_facets, &print_object, &layers, &edge_grids, &input_expolygons, &painted_lines, &painted_lines_mutex, &extruder_idx](const tbb::blocked_range<size_t> &range) {
+                const Transform3f tr = (object_trafo * mv->get_matrix()).cast<float>();
+                tbb::parallel_for(tbb::blocked_range<size_t>(0, custom_facets.indices.size()), [&tr, &custom_facets, &layers, &edge_grids, &input_expolygons, &painted_lines, &painted_lines_mutex, &extruder_idx](const tbb::blocked_range<size_t> &range) {
                    for (size_t facet_idx = range.begin(); facet_idx < range.end(); ++facet_idx) {
                        float min_z = std::numeric_limits<float>::max();
                        float max_z = std::numeric_limits<float>::lowest();
@@ -2102,7 +2110,6 @@ std::vector<std::vector<ExPolygons>> segmentation_by_painting(const PrintObject

                            Line line_to_test(Point(scale_(line_start_f.x()), scale_(line_start_f.y())),
                                              Point(scale_(line_end_f.x()), scale_(line_end_f.y())));
-                            line_to_test.translate(-print_object.center_offset());

                            // BoundingBoxes for EdgeGrids are computed from printable regions. It is possible that the painted line (line_to_test) could
                            // be outside EdgeGrid's BoundingBox, for example, when the negative volume is used on the painted area (GH #7618).
@@ -1124,7 +1124,7 @@ static std::vector<std::string> s_Preset_print_options{
    "top_surface_speed", "support_speed", "support_object_xy_distance", "support_object_first_layer_gap", "support_interface_speed",
    "bridge_speed", "internal_bridge_speed", "gap_infill_speed", "travel_speed", "travel_speed_z", "initial_layer_speed",
    "outer_wall_acceleration", "initial_layer_acceleration", "top_surface_acceleration", "default_acceleration", "skirt_type", "skirt_loops", "skirt_speed","min_skirt_length", "skirt_distance", "skirt_start_angle", "skirt_height","single_loop_draft_shield", "draft_shield",
-    "brim_width", "brim_object_gap", "brim_flow_ratio", "brim_use_efc_outline", "combine_brims", "brim_type", "brim_ears_max_angle", "brim_ears_detection_length", "brim_ears_outer_only", "enable_support", "support_type", "support_threshold_angle", "support_threshold_overlap","enforce_support_layers",
+    "brim_width", "leading_brim_length", "extra_brim_width", "brim_object_gap", "brim_flow_ratio", "brim_use_efc_outline", "combine_brims", "brim_type", "brim_ears_max_angle", "brim_ears_detection_length", "brim_ears_outer_only", "enable_support", "support_type", "support_threshold_angle", "support_threshold_overlap","enforce_support_layers",
    "raft_layers", "raft_first_layer_density", "raft_first_layer_expansion", "raft_contact_distance", "raft_expansion",
    "support_base_pattern", "support_base_pattern_spacing", "support_expansion", "support_style",
    // BBS
@@ -1194,6 +1194,8 @@ static std::vector<std::string> s_Preset_print_options{
    "prime_volume",
    "prime_tower_infill_gap",
    "prime_tower_flat_ironing",
+    "belt_purge_tower_width",
+    "belt_purge_tower_object",
    "enable_tower_interface_features",
    "enable_tower_interface_cooldown_during_tower",
    "wipe_tower_no_sparse_layers",
@@ -1439,8 +1441,17 @@ static std::vector<std::string> s_Preset_machine_limits_options {

 static std::vector<std::string> s_Preset_printer_options {
    "printer_technology",
-    "printable_area", "extruder_printable_area", "support_parallel_printheads", "parallel_printheads_count", "parallel_printheads_bed_exclude_areas", "bed_exclude_area","bed_custom_texture", "bed_custom_model", "gcode_flavor",
-     "gcode_skip_config_block", "fan_kickstart", "part_cooling_fan_min_pwm", "fan_speedup_time", "fan_speedup_overhangs",
+    "printable_area", "extruder_printable_area", "support_parallel_printheads", "parallel_printheads_count", "parallel_printheads_bed_exclude_areas", "bed_exclude_area","bed_custom_texture", "bed_custom_model", "build_plate_tilt_x", "build_plate_tilt_y", "belt_printer", "belt_printer_infinite_y",
+    "belt_slice_rotation", "belt_slice_rotation_angle", "belt_slice_rotation_global",
+    "preslice_remap_x", "preslice_remap_y", "preslice_remap_z", "preslice_remap_global",
+    "gcode_remap_x", "gcode_remap_y", "gcode_remap_z", "gcode_back_transform",
+    "belt_frame_tilt_decouple", "belt_frame_tilt_angle",
+    "belt_preslice_global",
+    "first_layer_plane", "first_layer_plane_offset", "first_layer_plane_thickness",
+    "belt_support_floor_offset", "belt_support_floor_mode", "belt_support_z_offset_mode",
+    "enable_belt_purge_tower",
+    "gcode_flavor", "gcode_skip_config_block",
+    "fan_kickstart", "part_cooling_fan_min_pwm", "fan_speedup_time", "fan_speedup_overhangs",
    "single_extruder_multi_material", "manual_filament_change", "file_start_gcode", "machine_start_gcode", "machine_end_gcode", "before_layer_change_gcode", "printing_by_object_gcode", "layer_change_gcode", "time_lapse_gcode", "wrapping_detection_gcode", "change_filament_gcode", "change_extrusion_role_gcode",
    "printer_model", "printer_variant", "printer_extruder_id", "printer_extruder_variant", "extruder_variant_list", "default_nozzle_volume_type",
    "printable_height", "extruder_printable_height", "extruder_clearance_radius", "extruder_clearance_height_to_lid", "extruder_clearance_height_to_rod",
@@ -18,6 +18,8 @@
 #include "Thread.hpp"
 #include "Time.hpp"
 #include "GCode.hpp"
+#include "BeltGCode.hpp"
+#include "BeltTransform.hpp"
 #include "GCode/WipeTower.hpp"
 #include "GCode/WipeTower2.hpp"
 #include "GCode/WipeTowerEstimate.hpp"
@@ -26,6 +28,7 @@
 #include "MaterialType.hpp"
 #include "Model.hpp"
 #include "format.hpp"
+#include "LocalesUtils.hpp"
 #include <float.h>

 #include <algorithm>
@@ -111,6 +114,16 @@ bool Print::invalidate_state_by_config_options(const ConfigOptionResolver & /* n
    // Cache the plenty of parameters, which influence the G-code generator only,
    // or they are only notes not influencing the generated G-code.
    static std::unordered_set<std::string> steps_gcode = {
+        // Belt printer G-code axis remap (only affects G-code output, not slicing).
+        "gcode_remap_x",
+        "gcode_remap_y",
+        "gcode_remap_z",
+        // Machine-frame transform (derived from belt tilt; only affects G-code output).
+        "belt_frame_tilt_decouple", "belt_frame_tilt_angle",
+        "gcode_back_transform",
+        "first_layer_plane", "first_layer_plane_offset", "first_layer_plane_thickness",
+        // Only inflates the GUI bed volume, like printable_area.
+        "belt_printer_infinite_y",
        //BBS
        "additional_cooling_fan_speed",
        "reduce_crossing_wall",
@@ -310,8 +323,26 @@ bool Print::invalidate_state_by_config_options(const ConfigOptionResolver & /* n
            // Spiral Vase forces different kind of slicing than the normal model:
            // In Spiral Vase mode, holes are closed and only the largest area contour is kept at each layer.
            // Therefore toggling the Spiral Vase on / off requires complete reslicing.
-            || opt_key == "spiral_mode") {
+            || opt_key == "spiral_mode"
+            // Build plate tilt changes slicing plane orientation.
+            || opt_key == "build_plate_tilt_x"
+            || opt_key == "build_plate_tilt_y"
+            // Belt printer transform options change the mesh geometry before slicing.
+            || opt_key == "belt_printer"
+            || opt_key == "belt_slice_rotation"
+            || opt_key == "belt_slice_rotation_angle"
+            || opt_key == "belt_slice_rotation_global"
+            || opt_key == "belt_preslice_global"
+            || opt_key == "preslice_remap_global"
+            || opt_key == "preslice_remap_x"
+            || opt_key == "preslice_remap_y"
+            || opt_key == "preslice_remap_z") {
            osteps.emplace_back(posSlice);
+        } else if (
+               opt_key == "belt_support_floor_offset"
+            || opt_key == "belt_support_floor_mode"
+            || opt_key == "belt_support_z_offset_mode") {
+            osteps.emplace_back(posSupportMaterial);
        } else if (
               opt_key == "print_sequence"
            || opt_key == "filament_type"
@@ -346,6 +377,7 @@ bool Print::invalidate_state_by_config_options(const ConfigOptionResolver & /* n
            || opt_key == "hot_plate_temp"
            || opt_key == "textured_plate_temp"
            || opt_key == "enable_prime_tower"
+            || opt_key == "enable_belt_purge_tower"
            || opt_key == "enable_wrapping_detection"
            || opt_key == "prime_tower_enable_framework"
            || opt_key == "prime_tower_width"
@@ -377,6 +409,7 @@ bool Print::invalidate_state_by_config_options(const ConfigOptionResolver & /* n
            || opt_key == "prime_volume"
            || opt_key == "flush_into_infill"
            || opt_key == "flush_into_support"
+            || opt_key == "belt_purge_tower_width"
            || opt_key == "initial_layer_infill_speed"
            || opt_key == "travel_speed"
            || opt_key == "travel_speed_z"
@@ -608,6 +641,9 @@ std::vector<ObjectID> Print::print_object_ids() const

 bool Print::has_infinite_skirt() const
 {
+    // Belt printer: no skirt support.
+    if (m_config.belt_printer.value)
+        return false;
    // Orca: unclear why (m_config.ooze_prevention && this->extruders().size() > 1) logic is here, removed.
    // return (m_config.draft_shield == dsEnabled && m_config.skirt_loops > 0) || (m_config.ooze_prevention && this->extruders().size() > 1);

@@ -616,6 +652,9 @@ bool Print::has_infinite_skirt() const

 bool Print::has_skirt() const
 {
+    // Belt printer: no skirt support.
+    if (m_config.belt_printer.value)
+        return false;
    return (m_config.skirt_height > 0);
 }

@@ -624,6 +663,24 @@ bool Print::has_brim() const
    return std::any_of(m_objects.begin(), m_objects.end(), [](PrintObject *object) { return object->has_brim(); });
 }

+bool Print::has_tilted_belt() const
+{
+    if (! m_config.belt_printer.value)
+        return false;
+    // A Z rotation leaves the belt floor flat (BeltTransform forces shear = 0) and no
+    // rotation at all means the machine is geometrically a flat bed.
+    const BeltRotationAxis axis = m_config.belt_slice_rotation.value;
+    if (axis != BeltRotationAxis::X && axis != BeltRotationAxis::Y)
+        return false;
+    const double tilt = std::abs(m_config.belt_slice_rotation_angle.value);
+    return tilt >= BELT_BRIM_MIN_TILT_DEG && tilt <= BELT_BRIM_MAX_TILT_DEG;
+}
+
+bool Print::has_belt_brim() const
+{
+    return std::any_of(m_objects.begin(), m_objects.end(), [](PrintObject *object) { return object->has_belt_brim(); });
+}
+
 //BBS
 std::vector<size_t> Print::layers_sorted_for_object(float start, float end, std::vector<LayerPtrs> &layers_of_objects, std::vector<BoundingBox> &boundingBox_for_objects, VecOfPoints &objects_instances_shift)
 {
@@ -1353,6 +1410,83 @@ StringObjectException Print::validate(std::vector<StringObjectException> *warnin
    if (extruders.empty())
        return { L("No extrusions under current settings.") };

+    // Belt printer validation: incompatible features.
+    if (m_config.belt_printer.value) {
+        for (const PrintObject *object : m_objects) {
+            if (object->config().raft_layers > 0)
+                return { L("Raft is not compatible with belt printer mode.") };
+        }
+        if (m_config.draft_shield != dsDisabled)
+            return { L("Draft shield is not compatible with belt printer mode.") };
+
+        // Belt brim spans many layers and owns the layers below the object, which
+        // spiral vase cannot share. The prime tower setting is no obstacle: belt
+        // printers never print the classic tower, and the belt purge prism is an
+        // ordinary object that never takes a brim.
+        if (this->has_belt_brim()) {
+            if (m_config.spiral_mode.value)
+                return { L("Brim is not compatible with spiral vase mode on a belt printer. "
+                           "Disable one of them.") };
+        }
+
+        for (const PrintObject *object : m_objects) {
+            const PrintObjectConfig &ocfg = object->config();
+            // Mirror PrintObject::has_belt_brim(): an inner-only brim needs a positive
+            // brim_width (leading/extra widen only the outer ring), so keep this
+            // predicate in step or the belt-brim warnings below would fire for a brim
+            // that has_belt_brim() rejects.
+            const bool wants_brim = ocfg.brim_type != btNoBrim
+                                 && (ocfg.brim_type == btInnerOnly
+                                         ? ocfg.brim_width.value > 0.
+                                         : (ocfg.brim_width.value > 0. || ocfg.leading_brim_length.value > 0.
+                                            || ocfg.extra_brim_width.value > 0.));
+            if (! wants_brim)
+                continue;
+
+            if (! this->has_tilted_belt()) {
+                if (std::abs(m_config.belt_slice_rotation_angle.value) > BELT_BRIM_MAX_TILT_DEG)
+                    warn(L("The belt is too steep for a brim, so no brim will be generated."),
+                         "brim_width", object->model_object());
+                else
+                    warn(L("A brim is only generated when the belt is tilted. Set a belt tilt angle, "
+                           "or remove the brim setting."),
+                         "brim_type", object->model_object());
+            }
+
+            if (ocfg.brim_type == btAutoBrim || ocfg.brim_type == btEar || ocfg.brim_type == btPainted)
+                warn(L("Belt printers support outer and inner brim only. Auto, Mouse ear and Painted "
+                       "brim are printed as Outer brim only, using Brim width."),
+                     "brim_type", object->model_object());
+
+            if (ocfg.leading_brim_length.value > 0. && ocfg.brim_object_gap.value > 0.)
+                warn(L("Brim-object gap separates the leading brim from the object's leading edge, "
+                       "which is the edge it is meant to anchor. Set the gap to 0 when using leading "
+                       "brim length."),
+                     "brim_object_gap", object->model_object());
+
+            // Unconditional: this suppresses the WHOLE belt brim, not just the apron, so a
+            // user asking for any brim at all needs to be told they are getting none.
+            if (! object->belt_brim_instances_compatible())
+                warn(L("This object's copies are spaced along the belt, so they would each need "
+                       "their own brim and none is generated. Print them as separate objects, or "
+                       "arrange the copies side by side across the belt."),
+                     "brim_type", object->model_object());
+        }
+        if (this->has_belt_brim() && m_objects.size() > 1)
+            warn(L("Leading brim length extends ahead of each object along the belt, and Arrange does "
+                   "not reserve that space. Leave room between objects."),
+                 "leading_brim_length");
+    } else {
+        // "Leading edge only" describes where a part meets a moving belt, so it has no
+        // meaning on a fixed bed.  Brim.cpp prints it as an ordinary outer brim rather
+        // than silently producing nothing; say so.
+        for (const PrintObject *object : m_objects)
+            if (object->config().brim_type == btLeadingEdgeOnly)
+                warn(L("\"Leading edge only\" brim applies to belt printers. On this printer it is "
+                       "printed as an ordinary outer brim."),
+                     "brim_type", object->model_object());
+    }
+
    // Orca: a gradient mixed filament only renders its gradient with "Mixed color sublayer" on;
    // without it ToolOrdering::resolve_mixed_filaments prints one whole component per layer and
    // the gradient is dropped silently. extruders() already covers painting, height ranges,
@@ -1408,6 +1542,40 @@ StringObjectException Print::validate(std::vector<StringObjectException> *warnin
            add_warning(layer_warning);
    }

+    if (m_config.belt_printer.value && m_config.enable_belt_purge_tower.value
+        && m_config.print_sequence == PrintSequence::ByObject
+        && extruders.size() > 1) {
+        StringObjectException warningtemp;
+        warningtemp.string     = L("The belt purge tower is not generated in \"By object\" print sequence; "
+                                   "filament changes will not be purged.");
+        warningtemp.opt_key    = "enable_belt_purge_tower";
+        warningtemp.is_warning = true;
+        add_warning(warningtemp);
+    }
+
+    // The purge tower is a model object the GUI creates and sizes; libslic3r only purges
+    // into one that exists. A project sliced without it (the CLI on a project saved before
+    // the tower was generated) changes filament with nowhere to purge.
+    if (m_config.belt_printer.value && m_config.enable_belt_purge_tower.value
+        && m_config.print_sequence != PrintSequence::ByObject
+        && ! m_config.spiral_mode.value && this->object_extruders().size() > 1 && ! this->has_belt_purge_tower()) {
+        StringObjectException warningtemp;
+        warningtemp.string     = L("The belt purge tower is enabled but the project has no purge tower object; "
+                                   "filament changes will not be purged. Open the project in the application "
+                                   "to generate the tower.");
+        warningtemp.opt_key    = "enable_belt_purge_tower";
+        warningtemp.is_warning = true;
+        add_warning(warningtemp);
+    }
+
+    if (m_config.belt_printer.value && m_config.enable_belt_purge_tower.value) {
+        const size_t prism_count = std::count_if(m_objects.begin(), m_objects.end(), [](const PrintObject *object) {
+            return object->config().belt_purge_tower_object.value;
+        });
+        if (prism_count > 1)
+            return {L("The project contains multiple managed belt purge towers. Reload the plate or toggle the belt purge tower off and on to regenerate it.")};
+    }
+
    if (m_config.enable_prime_tower) {
        for (const PrintObject* object : m_objects) {
            if (object->config().precise_z_height.value) {
@@ -1461,35 +1629,59 @@ StringObjectException Print::validate(std::vector<StringObjectException> *warnin
        return profile;
    };

-    // Checks that the print does not exceed the max print height
+    // Checks that the print does not exceed the max print height.
+    // For belt printers the slicing-frame Z spans the sheared X-length and
+    // is not comparable to printable_height (which is gantry clearance in the
+    // build-volume frame).  Compare against the model's pre-shear Z instead,
+    // mirroring the bbox computed in PrintObject::update_slicing_parameters.
+    // The machine-frame transform only changes how that height is written to
+    // G-code, not how much room there is under the gantry.
+    const bool belt_printer = this->config().belt_printer.value;
+    const double shrinkage_compensation_z = this->shrinkage_compensation().z();
    for (size_t print_object_idx = 0; print_object_idx < m_objects.size(); ++ print_object_idx) {
        const PrintObject &print_object = *m_objects[print_object_idx];
-        //FIXME It is quite expensive to generate object layers just to get the print height!
-        if (auto layers = generate_object_layers(print_object.slicing_parameters(), layer_height_profile(print_object_idx), print_object.config().precise_z_height.value);
-            !layers.empty()) {

-            Vec3d test =this->shrinkage_compensation();
-            const double shrinkage_compensation_z = this->shrinkage_compensation().z();
-            
-            if (shrinkage_compensation_z != 1. && layers.back() > (this->config().printable_height / shrinkage_compensation_z + EPSILON)) {
-                // The object exceeds the maximum build volume height because of shrinkage compensation.
-                return StringObjectException{
-                    Slic3r::format(_u8L("While the object %1% itself fits the build volume, it exceeds the maximum build volume height because of material shrinkage compensation."), print_object.model_object()->name),
-                    print_object.model_object(),
-                    ""
-                };
-            } else if (layers.back() > this->config().printable_height + EPSILON) {
-                // Test whether the last slicing plane is below or above the print volume.
-                return StringObjectException{
-                    0.5 * (layers[layers.size() - 2] + layers.back()) > this->config().printable_height + EPSILON ?
-                    Slic3r::format(_u8L("The object %1% exceeds the maximum build volume height."), print_object.model_object()->name) :
-                    Slic3r::format(_u8L("While the object %1% itself fits the build volume, its last layer exceeds the maximum build volume height."), print_object.model_object()->name) +
-                    " " + _u8L("You might want to reduce the size of your model or change current print settings and retry."),
-                    print_object.model_object(),
-                    ""
-                };
+        double effective_max_z       = 0;
+        bool   last_layer_below_max  = false;
+        bool   have_height           = false;
+
+        if (belt_printer) {
+            double raw_z = print_object.model_object()->max_z();
+            if (BeltTransformPipeline::has_preslice_remap(this->config()))
+                raw_z = BeltTransformPipeline::remap_bbox(*print_object.model_object(), this->config()).size().z();
+            effective_max_z = raw_z;
+            have_height     = raw_z > 0;
+        } else {
+            //FIXME It is quite expensive to generate object layers just to get the print height!
+            auto layers = generate_object_layers(print_object.slicing_parameters(), layer_height_profile(print_object_idx), print_object.config().precise_z_height.value);
+            if (!layers.empty()) {
+                effective_max_z      = layers.back();
+                last_layer_below_max = layers.size() >= 2 &&
+                    0.5 * (layers[layers.size() - 2] + layers.back()) <= this->config().printable_height + EPSILON;
+                have_height          = true;
            }
        }
+
+        if (!have_height)
+            continue;
+
+        if (shrinkage_compensation_z != 1. && effective_max_z > (this->config().printable_height / shrinkage_compensation_z + EPSILON)) {
+            // The object exceeds the maximum build volume height because of shrinkage compensation.
+            return StringObjectException{
+                Slic3r::format(_u8L("While the object %1% itself fits the build volume, it exceeds the maximum build volume height because of material shrinkage compensation."), print_object.model_object()->name),
+                print_object.model_object(),
+                ""
+            };
+        } else if (effective_max_z > this->config().printable_height + EPSILON) {
+            return StringObjectException{
+                last_layer_below_max ?
+                Slic3r::format(_u8L("While the object %1% itself fits the build volume, its last layer exceeds the maximum build volume height."), print_object.model_object()->name) +
+                " " + _u8L("You might want to reduce the size of your model or change current print settings and retry.") :
+                Slic3r::format(_u8L("The object %1% exceeds the maximum build volume height."), print_object.model_object()->name),
+                print_object.model_object(),
+                ""
+            };
+        }
    }

    // Some of the objects has variable layer height applied by painting or by a table.
@@ -1509,12 +1701,12 @@ StringObjectException Print::validate(std::vector<StringObjectException> *warnin
                    return {_u8L("Variable layer height is not supported with Organic supports.") };
        }

-    if (this->has_wipe_tower() && ! m_objects.empty()) {
+    if ((this->has_wipe_tower() || this->has_belt_purge_tower()) && ! m_objects.empty()) {
        // Orca: wipe_tower_filament (issue #10971) is inserted into the tool order after
        // resolve_mixed_filaments has expanded every mixed (virtual) slot, so a mixed slot here
        // would reach the G-code as a tool change to a slot no nozzle carries. The GUI hides
        // mixed slots from the option; this guards loaded projects and the CLI.
-        if (m_config.wipe_tower_filament > 0) {
+        if (this->has_wipe_tower() && m_config.wipe_tower_filament > 0) {
            const auto  &is_mixed = m_config.filament_is_mixed.values;
            const size_t wipe_idx = size_t(m_config.wipe_tower_filament - 1);
            if (wipe_idx < is_mixed.size() && is_mixed[wipe_idx])
@@ -1536,12 +1728,17 @@ StringObjectException Print::validate(std::vector<StringObjectException> *warnin
                }
        }

-        if (! m_config.use_relative_e_distances)
-            return { L("The Wipe Tower is currently only supported with the relative extruder addressing (use_relative_e_distances=1).") };
+        // The following two constraints come from the classic wipe tower G-code
+        // generator; purging into the belt purge prism uses normal object
+        // extrusions and does not need them.
+        if (this->has_wipe_tower()) {
+            if (! m_config.use_relative_e_distances)
+                return { L("The Wipe Tower is currently only supported with the relative extruder addressing (use_relative_e_distances=1).") };
+
+            if (m_config.ooze_prevention && m_config.single_extruder_multi_material)
+                return {L("Ooze prevention is only supported with the wipe tower when 'single_extruder_multi_material' is off.")};
+        }

-        if (m_config.ooze_prevention && m_config.single_extruder_multi_material)
-            return {L("Ooze prevention is only supported with the wipe tower when 'single_extruder_multi_material' is off.")};
-            
 #if 0
        if (m_config.gcode_flavor != gcfRepRapSprinter && m_config.gcode_flavor != gcfRepRapFirmware &&
            m_config.gcode_flavor != gcfRepetier && m_config.gcode_flavor != gcfMarlinLegacy && m_config.gcode_flavor != gcfMarlinFirmware)
@@ -2261,8 +2458,28 @@ BoundingBox PrintObject::get_first_layer_bbox(float& a, float& layer_height, std
            a += area(slice);
        }
    }
-    if (has_brim())
+    // Guard on `defined`: make_brim() can return before assigning this (it does on
+    // belt printers, where has_brim() is still true but the plate brim is skipped),
+    // and overwriting a valid bbox with an undefined one corrupted the first-layer
+    // centre and the GUI's first-layer area readout.
+    if (has_brim() && firstLayerObjectBrimBoundingBox.defined)
        bbox = firstLayerObjectBrimBoundingBox;
+    // Belt brim: the apron reaches ahead of the object along the belt.
+    if (has_belt_brim()) {
+        const Point shift = instances().empty() ? Point(0, 0) : instances()[0].shift_without_plate_offset();
+        for (const ExPolygons &areas : m_belt_brim_areas_by_layer)
+            for (const ExPolygon &ex : areas) {
+                BoundingBox bb = get_extents(ex.contour);
+                bb.translate(shift.x(), shift.y());
+                bbox.merge(bb);
+            }
+        for (const BeltBrimBand &band : m_belt_brim_prologue)
+            for (const ExPolygon &ex : band.areas) {
+                BoundingBox bb = get_extents(ex.contour);
+                bb.translate(shift.x(), shift.y());
+                bbox.merge(bb);
+            }
+    }
    return bbox;
 }

@@ -2309,6 +2526,19 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)
    if (m_objects.empty())
        return;

+    // Belt purge prism: _plan_belt_purge() (psWipeTower) truncates the prism's
+    // layers and drops its unclaimed fills, stashing both so a replan can undo
+    // them. The object steps below regenerate per-layer content over m_layers
+    // ONLY, so if any of them is about to rerun the stashes must go back first;
+    // otherwise truncated layers keep stale perimeters/fills and dropped fills
+    // are re-inserted next to freshly generated ones. Every object-step
+    // invalidation also invalidates psWipeTower, so "psWipeTower not done" is
+    // exactly "some object step may rerun" -- and when it IS done nothing below
+    // regenerates, and the plan's edits have to stay.
+    if (!this->is_step_done(psWipeTower))
+        for (PrintObject *obj : m_objects)
+            obj->belt_undo_purge_plan();
+
    for (PrintObject *obj : m_objects)
        obj->clear_shared_object();

@@ -2361,15 +2591,24 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)
    int object_count = m_objects.size();
    std::set<PrintObject*> need_slicing_objects;
    std::set<PrintObject*> re_slicing_objects;
+    // Belt global modes couple each object's bed position into its layer Z values,
+    // so sharing layers between "identical" objects is wrong.
+    bool belt_no_share = m_config.belt_printer.value &&
+        ((m_config.belt_slice_rotation_global.value
+              && m_config.belt_slice_rotation.value != BeltRotationAxis::None)
+         || m_config.preslice_remap_global.value
+         || m_config.belt_preslice_global.value);
    if (!use_cache) {
        for (int index = 0; index < object_count; index++)
        {
            PrintObject *obj =  m_objects[index];
-            for (PrintObject *slicing_obj : need_slicing_objects)
-            {
-                if (is_print_object_the_same(obj, slicing_obj)) {
-                    obj->set_shared_object(slicing_obj);
-                    break;
+            if (!belt_no_share) {
+                for (PrintObject *slicing_obj : need_slicing_objects)
+                {
+                    if (is_print_object_the_same(obj, slicing_obj)) {
+                        obj->set_shared_object(slicing_obj);
+                        break;
+                    }
                }
            }
            if (!obj->get_shared_object())
@@ -2388,12 +2627,14 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)
            PrintObject *obj =  m_objects[index];
            bool found_shared = false;
            if (need_slicing_objects.find(obj) == need_slicing_objects.end()) {
-                for (PrintObject *slicing_obj : need_slicing_objects)
-                {
-                    if (is_print_object_the_same(obj, slicing_obj)) {
-                        obj->set_shared_object(slicing_obj);
-                        found_shared = true;
-                        break;
+                if (!belt_no_share) {
+                    for (PrintObject *slicing_obj : need_slicing_objects)
+                    {
+                        if (is_print_object_the_same(obj, slicing_obj)) {
+                            obj->set_shared_object(slicing_obj);
+                            found_shared = true;
+                            break;
+                        }
                    }
                }
                if (!found_shared) {
@@ -2601,7 +2842,10 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)

        m_wipe_tower_data.clear();
        m_tool_ordering.clear();
-        if (this->has_wipe_tower()) {
+        if (this->has_belt_purge_tower() && this->config().print_sequence != PrintSequence::ByObject) {
+            this->_plan_belt_purge();
+        }
+        else if (this->has_wipe_tower()) {
            this->_make_wipe_tower();
        }
        else if (this->config().print_sequence != PrintSequence::ByObject) {
@@ -2849,6 +3093,26 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)
        }


+        // Belt brim: bound the first-layer convex hull by the lowest apron band, so
+        // bed levelling and the initial purge line account for brim that reaches
+        // ahead of every object.
+        if (this->has_belt_brim()) {
+            for (PrintObject *object : m_objects) {
+                if (! object->has_belt_brim() || object->belt_brim_prologue().empty())
+                    continue;
+                const BeltBrimBand &lowest = object->belt_brim_prologue().front();
+                for (const PrintInstance &instance : object->instances())
+                    for (const ExPolygon &ex : lowest.areas) {
+                        Polygon poly = ex.contour;
+                        poly.translate(instance.shift);
+                        append(m_first_layer_convex_hull.points, std::move(poly.points));
+                    }
+            }
+        }
+
+        // Unchanged for belt printers: _make_skirt() already returns early for them, and
+        // the belt brim does not populate m_brimMapByInstance, which is what the
+        // skirt/brim grouping reads.
        if (has_skirt() || has_infinite_skirt() || has_brim()) {
            // Generate skirt/brim groups after brim so per-object and draft-shield footprints
            // include brims when grouping and offsetting skirt loops.
@@ -2943,12 +3207,17 @@ std::string Print::export_gcode(const std::string& path_template, GCodeProcessor
    this->set_status(80, message);

    // The following line may die for multiple reasons.
-    GCode gcode;
+    // Factory: use BeltGCode for belt printers, plain GCode otherwise.
+    std::unique_ptr<GCode> gcode;
+    if (m_config.belt_printer.value)
+        gcode = std::make_unique<BeltGCode>();
+    else
+        gcode = std::make_unique<GCode>();
    //BBS: compute plate offset for gcode-generator
    const Vec3d origin = this->get_plate_origin();
-    gcode.set_gcode_offset(origin(0), origin(1));
-    gcode.do_export(this, path.c_str(), result, thumbnail_cb);
-    gcode.export_layer_filaments(result);
+    gcode->set_gcode_offset(origin(0), origin(1));
+    gcode->do_export(this, path.c_str(), result, thumbnail_cb);
+    gcode->export_layer_filaments(result);
    //BBS
    if (result != nullptr) {
        result->conflict_result = m_conflict_result;
@@ -2963,6 +3232,10 @@ std::string Print::export_gcode(const std::string& path_template, GCodeProcessor

 void Print::_make_skirt()
 {
+    // Belt printer: skirt is not compatible.
+    if (m_config.belt_printer.value)
+        return;
+  
    const bool generate_skirt = this->has_skirt() || this->has_infinite_skirt();

    // First off we need to decide how tall the skirt must be.
@@ -4003,6 +4276,13 @@ int Print::get_config_index(int filament_id, int layer_id, const std::vector<std
 // Wipe tower support.
 bool Print::has_wipe_tower() const
 {
+    // Belt printers never get the classic wipe tower: its G-code is generated
+    // directly in machine XY coordinates and bypasses the belt rotation
+    // transform. Purging is routed into the belt purge prism instead
+    // (see has_belt_purge_tower() / _plan_belt_purge()).
+    if (m_config.belt_printer.value)
+        return false;
+
    if (m_config.enable_prime_tower.value == true) {
        if (m_config.enable_wrapping_detection.value && m_config.wrapping_exclude_area.values.size() > 2)
            return true;
@@ -4015,6 +4295,7 @@ bool Print::has_wipe_tower() const
    return false;
 }

+
 const WipeTowerData &Print::wipe_tower_data(size_t filaments_cnt) const
 {
    // Until the tower is generated, size it with the estimate the GUI/CLI placement uses, so
@@ -4044,6 +4325,7 @@ bool Print::enable_timelapse_print() const
    return m_config.timelapse_type.value == TimelapseType::tlSmooth;
 }

+
 void Print::_make_wipe_tower()
 {
    m_wipe_tower_data.clear();
@@ -17,6 +17,8 @@
 #include "GCode/ThumbnailData.hpp"
 #include "GCode/GCodeProcessor.hpp"
 #include "MultiMaterialSegmentation.hpp"
+#include "BeltBrim.hpp"
+#include "BeltTransform.hpp"
 #include "ObjectID.hpp"
 #include "libslic3r.h"

@@ -205,6 +207,13 @@ class ConstSupportLayerPtrsAdaptor : public ConstVectorOfPtrsAdaptor<SupportLaye
    ConstSupportLayerPtrsAdaptor(const SupportLayerPtrs *data) : ConstVectorOfPtrsAdaptor<SupportLayer>(data) {}
 };

+// Returns the model's raw bounding box with pre-slice axis remap applied.
+// When no remap is active, returns the unmodified raw_bounding_box().
+inline BoundingBoxf3 belt_remapped_bbox(const ModelObject &model_object, const PrintConfig &config)
+{
+    return BeltTransformPipeline::remap_bbox(model_object, config);
+}
+
 // Single instance of a PrintObject.
 // As multiple PrintObjects may be generated for a single ModelObject (their instances differ in rotation around Z),
 // ModelObject's instancess will be distributed among these multiple PrintObjects.
@@ -350,6 +359,9 @@ public:
    // Trafo with the center_offset() applied after the transformation, to center the object in XY before slicing.
    Transform3d                  trafo_centered() const
        { Transform3d t = this->trafo(); t.pretranslate(Vec3d(- unscale<double>(m_center_offset.x()), - unscale<double>(m_center_offset.y()), 0)); return t; }
+    // trafo_centered() with the belt pre-slice transforms applied: the frame the layers were sliced in (Layer::slice_z).
+    // Equal to trafo_centered() unless a belt rotation or pre-slice remap is active.
+    Transform3d                  trafo_sliced() const;
    const PrintInstances&        instances() const      { return m_instances; }
    PrintInstances &instances() { return m_instances; }

@@ -389,6 +401,30 @@ public:
            && ! this->has_raft();
    }

+    // Belt brim.  A tilted belt needs its brim laid onto the belt plane over many
+    // layers instead of as one flat first-layer ring, so it is generated by
+    // BeltBrim.cpp and stored per layer here.  Deliberately separate from
+    // has_brim(): that predicate feeds PrintRegion extruder collection, support
+    // trimming and the spiral vase probe, and widening it would perturb belt
+    // support output.
+    bool                         has_belt_brim() const;
+    // Brim filament for this object's belt brim, returned in the 1-based domain of
+    // PrintRegion::outer_wall_filament_id and the raw values pushed into
+    // LayerTools::extruders in ToolOrdering::collect_extruders (ToolOrdering reindexes
+    // the whole list to 0-based afterwards).  Lowest positive outer_wall_filament_id
+    // over the printing regions, 1 if none is explicitly set.
+    unsigned int                 belt_brim_filament() const;
+    // False when this object's instances sit at different points ALONG the belt, which
+    // would need a separate set of bands each.  Public so validate() can explain it.
+    bool                         belt_brim_instances_compatible() const;
+    const std::vector<ExtrusionEntityCollection>& belt_brim_by_layer()       const { return m_belt_brim_by_layer; }
+    const std::vector<ExPolygons>&                belt_brim_areas_by_layer() const { return m_belt_brim_areas_by_layer; }
+    const std::vector<BeltBrimBand>&              belt_brim_prologue()       const { return m_belt_brim_prologue; }
+    void                         clear_belt_brim();
+    void                         set_belt_brim(std::vector<ExtrusionEntityCollection> &&by_layer,
+                                               std::vector<ExPolygons>                &&areas,
+                                               std::vector<BeltBrimBand>              &&prologue);
+
    // BBS
    const ExtrusionEntityCollection& object_skirt() const {
        return m_skirt;
@@ -538,6 +574,39 @@ private:
    std::vector<std::set<int>> detect_extruder_geometric_unprintables() const;

    void slice_volumes();
+    // Belt mode: shift the sliced layer grid (layer print_z and the belt floor
+    // clipping shift) by delta, used by Print::_align_belt_purge_layers() to
+    // snap the purge prism's layers onto the printed objects' layer grid.
+    void belt_shift_layer_grid(double delta);
+    // Belt mode: remove layers above z (cancel the purge prism past the last
+    // toolchange). Returns how many layers were dropped.
+    size_t belt_truncate_layers_above(coordf_t z);
+    // Restore layers removed by belt_truncate_layers_above() before replanning.
+    // Wipe-tower-only invalidations do not necessarily reslice the object, so
+    // truncation must be reversible when later toolchanges move upward.
+    void belt_restore_truncated_layers();
+    // Belt purge prism, plastic saving: drop the fills on one layer that no
+    // toolchange claimed. `claimed` reports whether an entity was overridden as
+    // purge; everything else on that layer would otherwise print as solid infill
+    // in the prism's own filament for nothing. Perimeters are never touched, so
+    // the bar keeps a continuous wall along the belt.
+    //
+    // Entities are STASHED, not deleted, with their original positions -- the
+    // same reversibility contract belt_truncate_layers_above() has, and the
+    // reason the original version of this had to be removed: psWipeTower can
+    // rerun without regenerating infill, and a later tool ordering may claim what
+    // this one did not. Returns the number of entities dropped.
+    size_t belt_drop_unclaimed_fills(Layer *layer, const std::function<bool(const ExtrusionEntity*)> &claimed);
+    // Put every stashed fill back at its original index. Must run before a replan.
+    void   belt_restore_dropped_fills();
+    // Undo every edit _plan_belt_purge() made to this object's layers, leaving
+    // m_layers exactly as the object steps produced it. Fills first: they point
+    // into layers that are still live, and truncated layers were stashed whole
+    // with their own fills untouched, so the two stashes never share an entity.
+    // Print::process() calls this before any object step may rerun (those steps
+    // regenerate per-layer content over m_layers only, so a stale stash would
+    // otherwise be restored on top of fresh content); the plan calls it too.
+    void   belt_undo_purge_plan() { belt_restore_dropped_fills(); belt_restore_truncated_layers(); }
    //BBS
    ExPolygons _shrink_contour_holes(double contour_delta, double hole_delta, const ExPolygons& polys) const;
    // BBS
@@ -580,7 +649,24 @@ private:

    SlicingParameters                       m_slicing_params;
    LayerPtrs                               m_layers;
+    LayerPtrs                               m_belt_truncated_layers;
+    // Fills removed by belt_drop_unclaimed_fills(), owned by this vector until
+    // restored or until clear_layers() deletes them. An entity is in exactly one
+    // of the live collection or this stash, never both.
+    struct BeltDroppedFill {
+        Layer           *layer      { nullptr };
+        size_t           region_idx { 0 };
+        size_t           index      { 0 };   // position in the original fills.entities
+        ExtrusionEntity *entity     { nullptr };
+    };
+    std::vector<BeltDroppedFill>            m_belt_dropped_fills;
    SupportLayerPtrs                        m_support_layers;
+    // Belt brim, generated in posSupportMaterial by BeltBrim.cpp.  Object-local
+    // slicing frame, one entry per object layer plus a prologue of brim-only
+    // bands that print below the object's first layer.
+    std::vector<ExtrusionEntityCollection>  m_belt_brim_by_layer;
+    std::vector<ExPolygons>                 m_belt_brim_areas_by_layer;
+    std::vector<BeltBrimBand>               m_belt_brim_prologue;
    // BBS
    std::shared_ptr<TreeSupportData>        m_tree_support_preview_cache;

@@ -599,7 +685,27 @@ private:

    PrintObject*                            m_shared_object{ nullptr };

-    
+    // Belt printer: global Z offset applied to this object's layers for shear positioning.
+    double                                  m_belt_global_z_offset { 0.0 };
+    // Belt printer: min_z of mesh after belt shear (before Z-shift), for z_offset calc.
+    double                                  m_belt_min_z { 0.0 };
+    // Belt printer: XY correction from global pre-slice mode, applied to G-code origin.
+    Vec2d                                   m_belt_global_xy_correction { Vec2d::Zero() };
+    // Belt printer: exact belt_floor_z_shift computed during posSlice from a
+    // vertex-level scan of the post-transform mesh.  Cached separately from
+    // m_slicing_params so that rebuilding m_slicing_params on a non-belt-affecting
+    // invalidation (e.g. support config change) doesn't replace the exact value
+    // with the bbox approximation seeded by create_from_config().  Cleared when
+    // posSlice is invalidated.
+    double                                  m_belt_floor_z_shift_cached { 0.0 };
+    bool                                    m_belt_floor_z_shift_cache_valid { false };
+public:
+    double belt_global_z_offset() const { return m_belt_global_z_offset; }
+    double belt_min_z() const { return m_belt_min_z; }
+    Vec2d  belt_global_xy_correction() const { return m_belt_global_xy_correction; }
+private:
+
+
    // SoftFever
    // 
    // object id
@@ -960,6 +1066,15 @@ public:
    bool                has_infinite_skirt() const;
    bool                has_skirt() const;
    bool                has_brim() const;
+    // True when the belt is tilted enough that the BELT plane, not the bed plane, is
+    // the adhesion surface.  The flat plate brim is geometrically meaningless then
+    // and must not run, whatever the per-object brim settings say - in particular
+    // brim_type "Auto", which has_brim() reports as enabled even at width 0.
+    bool                has_tilted_belt() const;
+    // True when at least one object actually gets a tilted-belt brim generated.
+    // Implies has_tilted_belt(), but additionally requires the object's own brim
+    // settings to ask for one.
+    bool                has_belt_brim() const;
    //BBS
    bool                has_auto_brim() const    {
        return std::any_of(m_objects.begin(), m_objects.end(), [](PrintObject* object) { return object->config().brim_type == btAutoBrim; });
@@ -1034,6 +1149,8 @@ public:

    // Wipe tower support.
    bool                        has_wipe_tower() const;
+    // Belt purge prism (belt-mode replacement for the wipe tower).
+    bool                        has_belt_purge_tower() const;
    const WipeTowerData&        wipe_tower_data(size_t filaments_cnt = 0) const;
    const ToolOrdering& 		tool_ordering() const { return m_tool_ordering; }

@@ -1283,6 +1400,12 @@ private:

    void                _make_skirt();
    void                _make_wipe_tower();
+    // Belt mode: route filament-change purging into the belt purge prism
+    // (flush-into-objects) without generating a classic wipe tower.
+    void                _plan_belt_purge();
+    // Belt mode: shift the purge prism's layer grid to match the printed
+    // objects' grid so toolchange layers find prism layers to purge into.
+    void                _align_belt_purge_layers();
    void                finalize_first_layer_convex_hull();
    void                update_filament_self_index_cache();
    // Deduplicates, per filament, the (extruder type x volume type) variants the grouping
@@ -1,6 +1,7 @@
 #include "ClipperUtils.hpp"
 #include "Model.hpp"
 #include "Print.hpp"
+#include "BeltTransform.hpp"
 #include "FilamentMixer.hpp"

 #include <boost/log/trivial.hpp>
@@ -136,22 +137,29 @@ struct PrintObjectTrafoAndInstances

 // Generate a list of trafos and XY offsets for instances of a ModelObject
 // Orca: Updated to include XYZ filament shrinkage compensation
-static std::vector<PrintObjectTrafoAndInstances> print_objects_from_model_object(const ModelObject &model_object, const Vec3d &shrinkage_compensation)
+static std::vector<PrintObjectTrafoAndInstances> print_objects_from_model_object(const ModelObject &model_object, const Vec3d &shrinkage_compensation, bool force_separate_instances = false)
 {
    std::set<PrintObjectTrafoAndInstances> trafos;
    PrintObjectTrafoAndInstances           trafo;
    //BBS: add useful logs for debug
    int index = 0;
+    int unique_counter = 0;
    for (ModelInstance *model_instance : model_object.instances) {
        if (model_instance->is_printable()) {
            // Orca: Updated with XYZ filament shrinkage compensation
            Geometry::Transformation model_instance_transformation = model_instance->get_transformation();
            trafo.trafo = model_instance_transformation.get_matrix_with_applied_shrinkage_compensation(shrinkage_compensation);
-            
+
            auto shift = Point::new_scale(trafo.trafo.data()[12], trafo.trafo.data()[13]);
            // Reset the XY axes of the transformation.
            trafo.trafo.data()[12] = 0;
            trafo.trafo.data()[13] = 0;
+            // Belt printer global mode: prevent instance grouping so each
+            // copy gets its own PrintObject with independent layer Z values.
+            // Add a tiny unique perturbation to the existing Z (don't replace
+            // it — the Z translation from ensure_on_bed must be preserved).
+            if (force_separate_instances)
+                trafo.trafo.data()[14] += 1e-10 * (++unique_counter);
            // Search or insert a trafo.
            auto it = trafos.emplace(trafo).first;
            const_cast<PrintObjectTrafoAndInstances&>(*it).instances.emplace_back(PrintInstance{ nullptr, model_instance, shift });
@@ -1233,6 +1241,17 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
            BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << boost::format(", i=%1%, key=%2%")%i %changed_keys[i];
        }
    }
+    // On belt printers the support tilt follows the slicing rotation. The GUI keeps the two in
+    // sync, but a CLI or 3MF edit of the rotation alone would otherwise leave supports on a stale tilt.
+    if (const auto *belt_opt = new_full_config.option<ConfigOptionBool>("belt_printer"); belt_opt && belt_opt->value) {
+        const auto *axis_opt  = new_full_config.option<ConfigOptionEnum<BeltRotationAxis>>("belt_slice_rotation");
+        const auto *angle_opt = new_full_config.option<ConfigOptionFloat>("belt_slice_rotation_angle");
+        if (axis_opt && angle_opt) {
+            const auto tilt = BeltTransformPipeline::physical_tilt(axis_opt->value, angle_opt->value);
+            new_full_config.set_key_value("build_plate_tilt_x", new ConfigOptionFloat(tilt.tilt_x_deg));
+            new_full_config.set_key_value("build_plate_tilt_y", new ConfigOptionFloat(tilt.tilt_y_deg));
+        }
+    }
    const ConfigOption* enable_support_option = new_full_config.option("enable_support");
    if (enable_support_option && enable_support_option->getBool())
        m_support_used = true;
@@ -1748,11 +1767,20 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
        PrintObjectPtrs print_objects_new;
        print_objects_new.reserve(std::max(m_objects.size(), m_model.objects.size()));
        bool new_objects = false;
+        bool belt_instances_shifted = false;
        // Walk over all new model objects and check, whether there are matching PrintObjects.
        for (ModelObject *model_object : m_model.objects) {
            ModelObjectStatus &model_object_status = const_cast<ModelObjectStatus&>(model_object_status_db.reuse(*model_object));
            // Orca: Updated for XYZ filament shrink compensation
-            model_object_status.print_instances = print_objects_from_model_object(*model_object, this->shrinkage_compensation());
+            // Belt global mode: force each instance into its own PrintObject
+            // so each gets independent layer Z values.
+            bool belt_force_separate = m_config.belt_printer.value && (
+                (m_config.belt_slice_rotation_global.value
+                    && m_config.belt_slice_rotation.value != BeltRotationAxis::None
+                    && std::abs(m_config.belt_slice_rotation_angle.value) > EPSILON)
+                || m_config.belt_preslice_global.value
+                || (m_config.preslice_remap_global.value && BeltTransformPipeline::has_preslice_remap(m_config)));
+            model_object_status.print_instances = print_objects_from_model_object(*model_object, this->shrinkage_compensation(), belt_force_separate);
            std::vector<const PrintObjectStatus*> old;
            old.reserve(print_object_status_db.count(*model_object));
            for (const PrintObjectStatus &print_object_status : print_object_status_db.get_range(*model_object))
@@ -1800,6 +1828,7 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
                    if (status != PrintBase::APPLY_STATUS_UNCHANGED) {
                        size_t extruder_num = new_full_config.option<ConfigOptionFloats>("nozzle_diameter")->size();
                        update_apply_status(status == PrintBase::APPLY_STATUS_INVALIDATED);
+                        belt_instances_shifted = true;
                    }
 					print_objects_new.emplace_back((*it_old)->print_object);
 					const_cast<PrintObjectStatus*>(*it_old)->status = PrintObjectStatus::Reused;
@@ -1835,6 +1864,20 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
                update_apply_status(object->invalidate_step(posSlice));
            }
        }
+
+        // Belt printer global mode: when any object's instances shifted,
+        // recompute m_belt_global_z_offset for ALL objects (it depends on
+        // min_shift across all objects, so one move affects everyone).
+        if (belt_instances_shifted
+            && m_config.belt_printer.value
+            && ((m_config.belt_slice_rotation_global.value
+                    && m_config.belt_slice_rotation.value != BeltRotationAxis::None
+                    && std::abs(m_config.belt_slice_rotation_angle.value) > EPSILON)
+                || m_config.belt_preslice_global.value
+                || (m_config.preslice_remap_global.value && BeltTransformPipeline::has_preslice_remap(m_config)))) {
+            for (PrintObject *object : m_objects)
+                update_apply_status(object->invalidate_step(posSlice));
+        }
    }

    //BBS: check the config again
@@ -1,7 +1,9 @@
 #include "PrintConfig.hpp"
 #include "PrintConfigConstants.hpp"
+#include "BeltTransform.hpp"
 #include "ClipperUtils.hpp"
 #include "Config.hpp"
+#include "Geometry.hpp"
 #include "FilamentMixer.hpp"
 #include "MaterialType.hpp"
 #include "I18N.hpp"
@@ -347,6 +349,52 @@ static t_config_enum_values s_keys_map_SlicingMode {
 };
 CONFIG_OPTION_ENUM_DEFINE_STATIC_MAPS(SlicingMode)

+static t_config_enum_values s_keys_map_BeltRotationAxis {
+    { "none", int(BeltRotationAxis::None) },
+    { "x",    int(BeltRotationAxis::X) },
+    { "y",    int(BeltRotationAxis::Y) },
+    { "z",    int(BeltRotationAxis::Z) },
+};
+CONFIG_OPTION_ENUM_DEFINE_STATIC_MAPS(BeltRotationAxis)
+
+static t_config_enum_values s_keys_map_RemapAxis {
+    { "pos_x", int(RemapAxis::PosX) },
+    { "pos_y", int(RemapAxis::PosY) },
+    { "pos_z", int(RemapAxis::PosZ) },
+    { "neg_x", int(RemapAxis::NegX) },
+    { "neg_y", int(RemapAxis::NegY) },
+    { "neg_z", int(RemapAxis::NegZ) },
+    { "rev_x", int(RemapAxis::RevX) },
+    { "rev_y", int(RemapAxis::RevY) },
+    { "rev_z", int(RemapAxis::RevZ) },
+};
+CONFIG_OPTION_ENUM_DEFINE_STATIC_MAPS(RemapAxis)
+
+static t_config_enum_values s_keys_map_BeltSupportFloorMode {
+    { "none",           int(BeltSupportFloorMode::None) },
+    { "generator_only", int(BeltSupportFloorMode::GeneratorOnly) },
+};
+CONFIG_OPTION_ENUM_DEFINE_STATIC_MAPS(BeltSupportFloorMode)
+
+static t_config_enum_values s_keys_map_BeltSupportZOffsetMode {
+    { "none",           int(BeltSupportZOffsetMode::None) },
+    { "unconditional",  int(BeltSupportZOffsetMode::Unconditional) },
+    { "raft_only",      int(BeltSupportZOffsetMode::RaftOnly) },
+};
+CONFIG_OPTION_ENUM_DEFINE_STATIC_MAPS(BeltSupportZOffsetMode)
+
+static t_config_enum_values s_keys_map_FirstLayerPlaneMode {
+    { "auto",        int(FirstLayerPlaneMode::Auto) },
+    { "xy",          int(FirstLayerPlaneMode::XY) },
+    { "yz",          int(FirstLayerPlaneMode::YZ) },
+    { "xz",          int(FirstLayerPlaneMode::XZ) },
+    { "belt_affine", int(FirstLayerPlaneMode::BeltAffine) },
+    // Back-compat alias: pre-rotation builds serialised this mode as
+    // "belt_shear".  Accept it on parse so old 3MFs / presets keep loading.
+    { "belt_shear",  int(FirstLayerPlaneMode::BeltAffine) },
+};
+CONFIG_OPTION_ENUM_DEFINE_STATIC_MAPS(FirstLayerPlaneMode)
+
 static t_config_enum_values s_keys_map_SupportMaterialPattern {
    { "rectilinear",        smpRectilinear },
    { "rectilinear-grid",   smpRectilinearGrid },
@@ -463,6 +511,7 @@ static const t_config_enum_values s_keys_map_BrimType = {
    {"auto_brim", btAutoBrim},  // BBS
    {"brim_ears", btEar},     // Orca
    {"painted", btPainted},  // BBS
+    {"leading_edge_only", btLeadingEdgeOnly},  // belt printers
 };
 CONFIG_OPTION_ENUM_DEFINE_STATIC_MAPS(BrimType)

@@ -1853,6 +1902,45 @@ void PrintConfigDef::init_fff_params()
    def->mode = comSimple;
    def->set_default_value(new ConfigOptionFloat(0.));

+    def = this->add("leading_brim_length", coFloat);
+    def->label = L("Leading brim length");
+    def->category = L("Support");
+    def->tooltip = L("Belt printers only. Extends the brim AHEAD of the object along the belt, on "
+                     "every downhill-facing edge of its contact area - both the object's first "
+                     "contact with the belt and any island that lands later. This apron is laid "
+                     "onto the belt before the object reaches it, so the leading edge has "
+                     "something already stuck down to hold on to.\n\n"
+                     "Measured on the belt surface, and added on top of Brim width: the brim "
+                     "reaches Brim-object gap + Leading brim length + Brim width ahead of the "
+                     "object. Set Brim-object gap to 0, or the apron will not touch the object it "
+                     "is meant to anchor.\n\n"
+                     "On a tilted belt each layer lays one strip of the brim, so the thickness of "
+                     "the resulting brim sheet is set by flow rather than by layer height. Use "
+                     "Brim flow ratio to tune it.\n\n"
+                     "Set to 0 to disable.");
+    def->sidetext = L("mm");	// millimeters, CIS languages need translation
+    def->min = 0;
+    def->max = 100;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(0.));
+
+    def = this->add("extra_brim_width", coFloat);
+    def->label = L("Extra brim width");
+    def->category = L("Support");
+    def->tooltip = L("Belt printers only. Widens the brim SIDEWAYS, across the belt, without "
+                     "extending it further ahead of or behind the object. Use it when a part needs "
+                     "more grip along its length than Brim width alone gives.\n\n"
+                     "Measured on the belt surface, and added on top of Brim width: the brim "
+                     "reaches Brim-object gap + Brim width + Extra brim width to either side of "
+                     "the object. To extend the brim ahead of the object instead, use Leading brim "
+                     "length.\n\n"
+                     "Set to 0 to disable.");
+    def->sidetext = L("mm");	// millimeters, CIS languages need translation
+    def->min = 0;
+    def->max = 100;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(0.));
+
    def = this->add("brim_type", coEnum);
    def->label = L("Brim type");
    def->category = L("Support");
@@ -1866,6 +1954,7 @@ void PrintConfigDef::init_fff_params()
    def->enum_values.emplace_back("inner_only");
    def->enum_values.emplace_back("outer_and_inner");
    def->enum_values.emplace_back("no_brim");
+    def->enum_values.emplace_back("leading_edge_only");
    def->enum_labels.emplace_back(L("Auto"));
    def->enum_labels.emplace_back(L("Mouse ear"));
    def->enum_labels.emplace_back(L("Painted"));
@@ -1873,6 +1962,7 @@ void PrintConfigDef::init_fff_params()
    def->enum_labels.emplace_back(L("Inner brim only"));
    def->enum_labels.emplace_back(L("Outer and inner brim"));
    def->enum_labels.emplace_back(L("No-brim"));
+    def->enum_labels.emplace_back(L("Leading edge only"));
    def->mode = comSimple;
    def->set_default_value(new ConfigOptionEnum<BrimType>(btAutoBrim));

@@ -7063,6 +7153,297 @@ void PrintConfigDef::init_fff_params()
    def->mode = comSimple;
    def->set_default_value(new ConfigOptionFloatOrPercent(50., true));

+    def = this->add("build_plate_tilt_x", coFloat);
+    def->label = L("Build plate tilt X");
+    def->category = L("Support");
+    def->tooltip = L("Tilt angle of the build plate along the X axis. "
+                     "A positive value tilts the plate so the +X side is higher, shifting gravity toward -X and increasing overhangs on the +X side. "
+                     "A negative value tilts the -X side higher. Set to 0 for no X-axis tilt. "
+                     "In belt printer mode, this is automatically synced to the belt angle.");
+    def->sidetext = u8"\u00B0";
+    def->min = -89;
+    def->max = 89;
+    def->mode = comExpert;
+    def->set_default_value(new ConfigOptionFloat(0.));
+
+    def = this->add("build_plate_tilt_y", coFloat);
+    def->label = L("Build plate tilt Y");
+    def->category = L("Support");
+    def->tooltip = L("Tilt angle of the build plate along the Y axis. "
+                     "A positive value tilts the plate so the +Y side is higher, shifting gravity toward -Y and increasing overhangs on the +Y side. "
+                     "A negative value tilts the -Y side higher. Set to 0 for no Y-axis tilt.");
+    def->sidetext = u8"\u00B0";
+    def->min = -89;
+    def->max = 89;
+    def->mode = comExpert;
+    def->set_default_value(new ConfigOptionFloat(0.));
+
+    def = this->add("belt_printer", coBool);
+    def->label = L("Enable belt printing");
+    def->category = L("Printable space");
+    def->tooltip = L("Enable belt printer mode. Belt printers use a conveyor belt as the build surface, "
+                     "tilted at an angle (typically 45 degrees). The slicer will rotate the slicing plane "
+                     "and transform G-code coordinates for the tilted build surface.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(false));
+
+    def = this->add("belt_printer_infinite_y", coBool);
+    def->label = L("Infinite Y axis");
+    def->category = L("Printable space");
+    def->tooltip = L("Enable infinite Y axis for belt printers. "
+                     "When enabled, the Y axis build volume limit is effectively removed, "
+                     "allowing objects of any length to be printed along the belt direction.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(true));
+
+    // Mesh rotation applied before slicing — the sole mesh-side belt transform AND
+    // the single source of truth for the physical belt tilt (bed rendering, support
+    // gravity tilt and bed-exclusion projection all derive their angle from this).
+    def = this->add("belt_slice_rotation", coEnum);
+    def->label = L("Belt tilt axis");
+    def->category = L("Printable space");
+    def->tooltip = L("Axis the mesh is rotated about before slicing. This is the belt "
+                     "printer's tilt: an isometric (no distortion) rotation that also "
+                     "drives bed rendering and support gravity tilt, and that the g-code "
+                     "back-transform inverts before the machine-frame shear/scale and remap. "
+                     "X is the typical gantry tilt (belt travels along Y).");
+    def->enum_keys_map = &ConfigOptionEnum<BeltRotationAxis>::get_enum_values();
+    def->enum_values  = {"none", "x", "y", "z"};
+    def->enum_labels  = {L("None"), L("X"), L("Y"), L("Z")};
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionEnum<BeltRotationAxis>(BeltRotationAxis::X));
+
+    def = this->add("belt_slice_rotation_angle", coFloat);
+    def->label = L("Belt tilt angle");
+    def->category = L("Printable space");
+    def->tooltip = L("Tilt angle of the belt surface, in degrees. Most belt printers use "
+                     "45°. Positive values rotate counter-clockwise looking down the "
+                     "positive tilt axis; the magnitude is also the physical belt tilt "
+                     "used for bed rendering and support gravity.");
+    def->sidetext = L("°");
+    def->min = -180.;
+    def->max = 180.;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(45.));
+
+    def = this->add("belt_slice_rotation_global", coBool);
+    def->label = L("Global");
+    def->category = L("Printable space");
+    def->tooltip = L("Treat the slicing rotation as part of the global forward transform "
+                     "that BeltBackTransform inverts before the machine-frame remap. "
+                     "Required for rotation-mode belt printers. "
+                     "Defaults to on because virtually all rotation-mode printers need it.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(true));
+
+    def = this->add("belt_frame_tilt_decouple", coBool);
+    def->label = L("Decouple machine-frame tilt");
+    def->category = L("Printable space");
+    def->tooltip = L("Expert override: set the machine-frame (g-code shear/scale) tilt angle "
+                     "independently of the pre-slice rotation angle. When disabled, the "
+                     "machine-frame transform is derived from the belt tilt angle, so a single "
+                     "angle drives both stages. Enable only to compensate for a machine whose "
+                     "physical gantry tilt differs from the slicing rotation.");
+    def->mode = comExpert;
+    def->set_default_value(new ConfigOptionBool(false));
+
+    def = this->add("belt_frame_tilt_angle", coFloat);
+    def->label = L("Machine-frame tilt angle");
+    def->category = L("Printable space");
+    def->tooltip = L("Tilt angle (degrees) used to derive the machine-frame shear (tan) and "
+                     "scale (1/cos) applied to G-code. Only used when 'Decouple machine-frame "
+                     "tilt' is enabled; otherwise the belt tilt angle is used.");
+    def->sidetext = L("°");
+    def->min = -89.9;
+    def->max = 89.9;
+    def->mode = comExpert;
+    def->set_default_value(new ConfigOptionFloat(45.));
+
+    // G-code axis remap with sign
+    auto add_belt_remap = [this](const char *key, const char *label, const char *tooltip,
+                                  RemapAxis default_axis, ConfigOptionMode mode = comSimple) {
+        auto def = this->add(key, coEnum);
+        def->label = L(label);
+        def->category = L("Printable space");
+        def->tooltip = L(tooltip);
+        def->enum_keys_map = &ConfigOptionEnum<RemapAxis>::get_enum_values();
+        def->enum_values  = {"pos_x", "pos_y", "pos_z", "neg_x", "neg_y", "neg_z", "rev_x", "rev_y", "rev_z"};
+        def->enum_labels  = {L("+X"), L("+Y"), L("+Z"), L("-X"), L("-Y"), L("-Z"), L("Rev X"), L("Rev Y"), L("Rev Z")};
+        def->mode = mode;  // Visibility may also be gated by toggle_line in Tab.cpp
+        def->set_default_value(new ConfigOptionEnum<RemapAxis>(default_axis));
+    };
+
+    add_belt_remap("preslice_remap_x", "X",
+        "Before slicing, which model-space axis becomes the slicer's X axis. "
+        "Use this to re-orient the coordinate system so the slicer's XY plane matches "
+        "your belt printer's physical bed plane. For a printer whose bed is in the XZ plane, "
+        "set Y to +Z and Z to +Y (or -Y) to swap the vertical and belt-travel axes. "
+        "Default +X: no change.",
+        RemapAxis::PosX, comDevelop);
+    add_belt_remap("preslice_remap_y", "Y",
+        "Before slicing, which model-space axis becomes the slicer's Y axis. "
+        "The slicer treats Y as one of the two horizontal bed axes. If your physical "
+        "belt surface runs along the Z axis, map Y to +Z here so the slicer slices "
+        "along the correct plane. Default +Y: no change.",
+        RemapAxis::PosY, comDevelop);
+    add_belt_remap("preslice_remap_z", "Z",
+        "Before slicing, which model-space axis becomes the slicer's Z axis (layer stacking direction). "
+        "The slicer builds layers upward along this axis. If your printer's layer-stacking "
+        "direction is the physical Y axis, map Z to +Y (or -Y for inverted direction). "
+        "Rev mode mirrors relative to the build volume maximum. Default +Z: no change.",
+        RemapAxis::PosZ, comDevelop);
+
+    def = this->add("preslice_remap_global", coBool);
+    def->label = L("Global");
+    def->category = L("Printable space");
+    def->tooltip = L("When enabled, the pre-slice axis remap accounts for each object's bed position. "
+                      "Without this, the remap is applied locally around each object's center, so "
+                      "objects at different positions don't get a position-dependent contribution. "
+                      "Mirrors the 'Global' option on the belt slicing rotation, but for the remap.");
+    def->mode = comDevelop;
+    def->set_default_value(new ConfigOptionBool(false));
+
+    add_belt_remap("gcode_remap_x", "X", "Which slicing axis maps to machine X in G-code output. Applied AFTER slicing, during G-code generation.", RemapAxis::PosX, comDevelop);
+    add_belt_remap("gcode_remap_y", "Y", "Which slicing axis maps to machine Y in G-code output. Applied AFTER slicing, during G-code generation.", RemapAxis::PosY, comDevelop);
+    add_belt_remap("gcode_remap_z", "Z", "Which slicing axis maps to machine Z in G-code output. Applied AFTER slicing, during G-code generation.", RemapAxis::PosZ, comDevelop);
+
+    // The machine-frame G-code transform (shear + scale) is no longer configured
+    // by per-axis keys: it is derived from the belt tilt (belt_slice_rotation axis
+    // + angle, or belt_frame_tilt_angle when decoupled) in MachineFrameTransform.
+
+    def = this->add("gcode_back_transform", coBool);
+    def->label = L("G-code back-transform");
+    def->category = L("Printable space");
+    def->tooltip = L("Undo the pre-slice mesh transform before applying the G-code axis remap "
+                      "and machine-frame shear/scale. Required for the standard belt-printer "
+                      "rotation pipeline.");
+    def->mode = comExpert;
+    def->set_default_value(new ConfigOptionBool(true));
+
+    def = this->add("belt_preslice_global", coBool);
+    def->label = L("Global mesh transforms");
+    def->category = L("Printable space");
+    def->tooltip = L("When enabled, pre-slice belt transforms (remap, shear, scale) account for "
+                      "each object's bed position, producing correct machine coordinates without "
+                      "relying on origin snap. Each instance gets its own PrintObject.");
+    def->mode = comExpert;
+    def->set_default_value(new ConfigOptionBool(true));
+
+    // First-layer plane: which surface defines "first layer" for fan / speed /
+    // accel decisions.  On belt printers the slicing-frame layer 0 is a tilted
+    // slab that no longer corresponds to the physical first printed layer.
+    // Auto picks BeltAffine when any belt-side affine transform is active
+    // (Z shear or slicing rotation), otherwise XY (legacy).
+    def = this->add("first_layer_plane", coEnum);
+    def->label = L("First layer plane");
+    def->category = L("Printable space");
+    def->tooltip = L("Selects the reference plane used to decide which extrusions get "
+                     "first-layer settings (no fan, slow speed, initial-layer accel/jerk, "
+                     "deferred temperature drop). On belt printers a single slicing layer "
+                     "contains paths at many machine-Z values, so layer-index based detection "
+                     "fails. Auto resolves to Belt affine plane when any belt-side affine "
+                     "transform (Z shear or slicing rotation) is active, otherwise XY (legacy). "
+                     "Pick XY explicitly to opt out and force the legacy slicing-layer-0 "
+                     "detection.");
+    def->enum_keys_map = &ConfigOptionEnum<FirstLayerPlaneMode>::get_enum_values();
+    def->enum_values   = {"auto", "xy", "yz", "xz", "belt_affine"};
+    def->enum_labels   = {L("Auto"), L("XY (machine bed)"), L("YZ"), L("XZ"), L("Belt affine plane")};
+    def->mode = comExpert;
+    // Auto, not BeltAffine: BeltAffine activates the plane evaluator unconditionally, so on a
+    // non-belt printer on_first_layer(point) stopped agreeing with the legacy slicing-layer-0
+    // test and first-layer speeds were skipped (brim printed at the volumetric fallback rather
+    // than initial_layer_speed). Auto resolves to BeltAffine only when belt_printer is set with
+    // a non-zero slicing rotation, and to XY (evaluator inactive, legacy behaviour) otherwise --
+    // which is what this option's own description promises.
+    def->set_default_value(new ConfigOptionEnum<FirstLayerPlaneMode>(FirstLayerPlaneMode::Auto));
+
+    def = this->add("first_layer_plane_offset", coFloat);
+    def->label = L("Belt plane offset");
+    def->category = L("Printable space");
+    def->tooltip = L("Shifts the first-layer plane along its normal (mm). For axis-aligned "
+                     "planes this is just a coordinate shift. Positive values move the plane "
+                     "away from the belt surface (deeper into the model).");
+    def->sidetext = L("mm");
+    def->min = -1000;
+    def->max =  1000;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(0.0));
+
+    def = this->add("first_layer_plane_thickness", coFloat);
+    def->label = L("Plane band thickness");
+    def->category = L("Printable space");
+    def->tooltip = L("Thickness of one 'band' relative to the first-layer plane, in mm. "
+                     "Used as the unit by which 'No cooling for the first N layers' (and "
+                     "similar layer-count thresholds) is multiplied when the first-layer "
+                     "plane is active. -1 means use initial_layer_print_height.");
+    def->sidetext = L("mm");
+    def->min = -1;
+    def->max = 100;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(-1.0));
+
+    // Belt support floor debug controls
+    def = this->add("belt_support_floor_offset", coFloat);
+    def->label = L("Support Floor Z offset");
+    def->category = L("Printable space");
+    def->tooltip = L("Shifts the computed belt floor up or down (mm). Negative values lower the floor, allowing more supports to survive. Use this to diagnose belt floor formula issues.");
+    def->sidetext = L("mm");
+    def->min = -500;
+    def->max = 500;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(0));
+
+    {
+        auto def = this->add("belt_support_floor_mode", coEnum);
+        def->label = L("Floor mode");
+        def->category = L("Printable space");
+        def->tooltip = L("Controls belt floor awareness for supports. 'None' disables belt floor logic. "
+                         "'Generator only' stops support generation at the belt floor plane.");
+        def->enum_keys_map = &ConfigOptionEnum<BeltSupportFloorMode>::get_enum_values();
+        def->enum_values  = {"none", "generator_only"};
+        def->enum_labels  = {L("None"), L("Generator only")};
+        def->mode = comDevelop;
+        def->set_default_value(new ConfigOptionEnum<BeltSupportFloorMode>(BeltSupportFloorMode::GeneratorOnly));
+    }
+
+    {
+        auto def = this->add("belt_support_z_offset_mode", coEnum);
+        def->label = L("Z offset mode");
+        def->category = L("Printable space");
+        def->tooltip = L("How global Z offset is applied to support layers for belt printers with global shear. "
+                         "'None' = don't offset. 'Unconditional' = offset all layers. 'Raft only' = only offset raft layers.");
+        def->enum_keys_map = &ConfigOptionEnum<BeltSupportZOffsetMode>::get_enum_values();
+        def->enum_values  = {"none", "unconditional", "raft_only"};
+        def->enum_labels  = {L("None"), L("Unconditional"), L("Raft only")};
+        def->mode = comExpert;
+        def->set_default_value(new ConfigOptionEnum<BeltSupportZOffsetMode>(BeltSupportZOffsetMode::Unconditional));
+    }
+
+    def = this->add("enable_belt_purge_tower", coBool);
+    def->label = L("Enable belt purge tower");
+    def->category = L("Multimaterial");
+    def->tooltip = L("Belt-printer replacement for the wipe/prime tower. When enabled on a belt "
+                     "printer, a purge prism is automatically generated next to the printed parts "
+                     "and filament-change purging is routed into it (the classic wipe tower cannot "
+                     "be used on belt printers because its G-code bypasses the belt transform). "
+                     "Only available on belt printers.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(false));
+
+    def = this->add("belt_purge_tower_width", coFloat);
+    def->label = L("Belt purge tower width");
+    def->category = L("Printable space");
+    def->tooltip = L("Width (machine X, across the belt) of the purge prism that is automatically "
+                     "generated on belt printers when the prime tower is enabled and multiple "
+                     "filaments are used. Filament-change purging is routed into this prism's "
+                     "extrusions instead of a classic wipe tower. Its height is computed "
+                     "automatically from the worst-case purge volume per layer: a wider prism "
+                     "results in a shorter one.");
+    def->sidetext = L("mm");
+    def->min = 1.;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(35.));
+
    def = this->add("tree_support_branch_angle", coFloat);
    def->label = L("Tree support branch angle");
    def->category = L("Support");
@@ -7716,6 +8097,16 @@ void PrintConfigDef::init_fff_params()
        "It will not take effect unless the prime tower is enabled.");
    def->set_default_value(new ConfigOptionBool(false));

+    // Internal marker (not shown in any settings tab): identifies the auto-generated
+    // belt purge prism so it can be updated/removed by the auto-manager and aligned
+    // to the object layer grid by the backend. Persisted to 3mf like any per-object key.
+    def = this->add("belt_purge_tower_object", coBool);
+    def->category = L("Flush options");
+    def->label = L("Belt purge tower object");
+    def->tooltip = L("Marks the auto-generated belt purge prism. Managed automatically; do not set manually.");
+    def->mode = comDevelop;
+    def->set_default_value(new ConfigOptionBool(false));
+
    def = this->add("wipe_tower_bridging", coFloat);
    def->label = L("Maximal bridging distance");
    def->tooltip = L("Maximal distance between supports on sparse infill sections.");
@@ -8961,6 +9352,9 @@ void PrintConfigDef::handle_legacy(t_config_option_key &opt_key, std::string &va
    //BBS: handle legacy options
    if (opt_key == "curr_bed_type" && value == "SuperTack Plate") {
        value = "Supertack Plate";
+    } else if (opt_key == "belt_support_floor_mode" && (value == "clip_only" || value == "both")) {
+        // Never implemented; both behaved like "none".
+        value = "none";
    } else if (opt_key == "enable_wipe_tower") {
        opt_key = "enable_prime_tower";
    } else if (opt_key == "wipe_tower_width") {
@@ -12729,10 +13123,22 @@ Polygons get_bed_excluded_area(const PrintConfig& cfg)
 {
    const Pointfs exclude_area_points = cfg.bed_exclude_area.values;

+    // Belt printer: project exclusion zone points from the belt surface to machine-frame XY.
+    // On the belt surface Z=0, so the in-plane axis foreshortens by cos(tilt).  The tilt
+    // axis decides which bed axis foreshortens: tilt about X (belt along Y) scales Y,
+    // tilt about Y (belt along X) scales X.  Derived from belt_slice_rotation.
+    const bool is_belt = cfg.belt_printer.value;
+    const auto tilt    = BeltTransformPipeline::physical_tilt(
+        cfg.belt_slice_rotation.value, cfg.belt_slice_rotation_angle.value);
+    const double cos_x = is_belt ? std::cos(Geometry::deg2rad(tilt.tilt_x_deg)) : 1.0; // foreshortens Y
+    const double cos_y = is_belt ? std::cos(Geometry::deg2rad(tilt.tilt_y_deg)) : 1.0; // foreshortens X
+
    Polygon exclude_poly;
    for (int i = 0; i < exclude_area_points.size(); i++) {
        auto pt = exclude_area_points[i];
-        exclude_poly.points.emplace_back(scale_(pt.x()), scale_(pt.y()));
+        double x = is_belt ? pt.x() * cos_y : pt.x();
+        double y = is_belt ? pt.y() * cos_x : pt.y();
+        exclude_poly.points.emplace_back(scale_(x), scale_(y));
    }

    exclude_poly.make_counter_clockwise();
@@ -252,6 +252,59 @@ enum class SlicingMode
    CloseHoles,
 };

+// Axis around which the mesh is rotated before slicing, when
+// `belt_slice_rotation` is set.  None disables the rotation stage.  This is the
+// single "belt tilt" axis: it drives both the pre-slice mesh rotation and the
+// post-slice machine-frame transform (shear + scale derived from the tilt angle).
+enum class BeltRotationAxis
+{
+    None = 0,
+    X    = 1,
+    Y    = 2,
+    Z    = 3,
+};
+
+enum class RemapAxis
+{
+    PosX = 0, PosY = 1, PosZ = 2,
+    NegX = 3, NegY = 4, NegZ = 5,
+    RevX = 6, RevY = 7, RevZ = 8,  // Reversed: max - pos
+};
+
+enum class BeltSupportFloorMode
+{
+    None,           // No belt floor awareness
+    GeneratorOnly,  // Only in tree support drop_nodes/contact_points
+};
+
+enum class BeltSupportZOffsetMode
+{
+    None,           // Don't apply global_z_offset to support layers
+    Unconditional,  // Apply to all support layers
+    RaftOnly,       // Only apply to raft layers
+};
+
+// Selects which plane the slicer treats as the "first layer plane" — the
+// reference surface used to decide which extrusions get first-layer settings
+// (no fan, slow speed, initial-layer accel/jerk, deferred temperature drop).
+//
+// Auto resolves to:
+//   - XY (inactive, legacy behavior) for non-belt printers and for belt
+//     printers with no active belt-side transform.
+//   - BeltAffine for belt printers with any active belt-side affine
+//     transform (Z shear, slicing rotation, or both).
+//
+// XY is also used as an explicit "opt out" mode that forces legacy
+// per-layer first-layer detection even on belt printers.
+enum class FirstLayerPlaneMode
+{
+    Auto = 0,
+    XY,
+    YZ,
+    XZ,
+    BeltAffine,   // formerly BeltShear; renamed to reflect rotation support
+};
+
 enum SupportMaterialPattern {
    smpDefault,
    smpRectilinear, smpRectilinearGrid, smpHoneycomb,
@@ -359,6 +412,10 @@ enum BrimType {
    btInnerOnly,
    btOuterAndInner,
    btNoBrim,
+    // Belt printers: brim only where the part first touches the belt, nothing after
+    // that.  Appended last so no existing value shifts.  On a non-belt printer this
+    // has no meaning and behaves as btOuterOnly.
+    btLeadingEdgeOnly,
 };

 enum TimelapseType : int {
@@ -670,6 +727,11 @@ CONFIG_OPTION_ENUM_DECLARE_STATIC_MAPS(NoiseType)
 CONFIG_OPTION_ENUM_DECLARE_STATIC_MAPS(InfillPattern)
 CONFIG_OPTION_ENUM_DECLARE_STATIC_MAPS(IroningType)
 CONFIG_OPTION_ENUM_DECLARE_STATIC_MAPS(SlicingMode)
+CONFIG_OPTION_ENUM_DECLARE_STATIC_MAPS(BeltRotationAxis)
+CONFIG_OPTION_ENUM_DECLARE_STATIC_MAPS(RemapAxis)
+CONFIG_OPTION_ENUM_DECLARE_STATIC_MAPS(BeltSupportFloorMode)
+CONFIG_OPTION_ENUM_DECLARE_STATIC_MAPS(BeltSupportZOffsetMode)
+CONFIG_OPTION_ENUM_DECLARE_STATIC_MAPS(FirstLayerPlaneMode)
 CONFIG_OPTION_ENUM_DECLARE_STATIC_MAPS(SupportMaterialPattern)
 CONFIG_OPTION_ENUM_DECLARE_STATIC_MAPS(SupportMaterialStyle)
 CONFIG_OPTION_ENUM_DECLARE_STATIC_MAPS(SupportMaterialInterfacePattern)
@@ -1111,6 +1173,8 @@ PRINT_CONFIG_CLASS_DEFINE(
    ((ConfigOptionBool,                brim_use_efc_outline))
    ((ConfigOptionEnum<BrimType>,      brim_type))
    ((ConfigOptionFloat,               brim_width))
+    ((ConfigOptionFloat,               leading_brim_length))
+    ((ConfigOptionFloat,               extra_brim_width))
    ((ConfigOptionFloat,               brim_ears_detection_length))
    ((ConfigOptionFloat,               brim_ears_max_angle))
    ((ConfigOptionBool,                brim_ears_outer_only))
@@ -1194,6 +1258,9 @@ PRINT_CONFIG_CLASS_DEFINE(
    // BBS
    ((ConfigOptionBool,                flush_into_infill))
    ((ConfigOptionBool,                flush_into_support))
+    // Marker for the auto-generated belt purge prism; identifies the object to
+    // the auto-manager (GUI) and the layer-grid alignment step (backend).
+    ((ConfigOptionBool,                belt_purge_tower_object))
    // BBS
    ((ConfigOptionFloat,              tree_support_branch_distance))
    ((ConfigOptionFloat,              tree_support_tip_diameter))
@@ -1744,6 +1811,45 @@ PRINT_CONFIG_CLASS_DERIVED_DEFINE(
    PrintConfig,
    (MachineEnvelopeConfig, GCodeConfig),

+    // Build plate tilt for off-axis gravity support generation (printer-level setting).
+    ((ConfigOptionFloat,               build_plate_tilt_x))
+    ((ConfigOptionFloat,               build_plate_tilt_y))
+    // Belt printer settings (printer-level).
+    ((ConfigOptionBool,                belt_printer))
+    ((ConfigOptionBool,                belt_printer_infinite_y))
+    // Mesh rotation applied before slicing — the single source of truth for the
+    // physical belt tilt.  Its angle + axis drive bed rendering, support gravity
+    // tilt, the bed-exclusion projection, AND the post-slice machine-frame
+    // transform (shear + scale, derived from the tilt angle; see
+    // MachineFrameTransform).  Isometric (no distortion) on the mesh side; the
+    // g-code back-transform inverts the rotation before the machine-frame stage.
+    ((ConfigOptionEnum<BeltRotationAxis>, belt_slice_rotation))
+    ((ConfigOptionFloat,                  belt_slice_rotation_angle))
+    ((ConfigOptionBool,                   belt_slice_rotation_global))
+    // Expert override: decouple the machine-frame tilt angle from the pre-slice
+    // rotation angle.  When disabled, the machine frame uses belt_slice_rotation_angle.
+    ((ConfigOptionBool,                   belt_frame_tilt_decouple))
+    ((ConfigOptionFloat,                  belt_frame_tilt_angle))
+    ((ConfigOptionEnum<RemapAxis>,  preslice_remap_x))
+    ((ConfigOptionEnum<RemapAxis>,  preslice_remap_y))
+    ((ConfigOptionEnum<RemapAxis>,  preslice_remap_z))
+    ((ConfigOptionBool,             preslice_remap_global))
+    ((ConfigOptionEnum<RemapAxis>,  gcode_remap_x))
+    ((ConfigOptionEnum<RemapAxis>,  gcode_remap_y))
+    ((ConfigOptionEnum<RemapAxis>,  gcode_remap_z))
+    ((ConfigOptionBool,                 gcode_back_transform))
+    ((ConfigOptionBool,                 belt_preslice_global))
+    ((ConfigOptionEnum<FirstLayerPlaneMode>, first_layer_plane))
+    ((ConfigOptionFloat,                first_layer_plane_offset))
+    ((ConfigOptionFloat,                first_layer_plane_thickness))
+    ((ConfigOptionFloat,                          belt_support_floor_offset))
+    ((ConfigOptionEnum<BeltSupportFloorMode>,     belt_support_floor_mode))
+    ((ConfigOptionEnum<BeltSupportZOffsetMode>,   belt_support_z_offset_mode))
+    // Width (machine X, across the belt) of the auto-generated belt purge prism.
+    ((ConfigOptionFloat,                          belt_purge_tower_width))
+    // Belt-printer-only "type" of purge tower: enables the auto-generated belt
+    // purge prism (the belt replacement for the classic wipe/prime tower).
+    ((ConfigOptionBool,                           enable_belt_purge_tower))
    //BBS
    ((ConfigOptionInts,               additional_cooling_fan_speed))
    ((ConfigOptionInts,               close_additional_fan_first_x_layers))
@@ -2,6 +2,8 @@
 #include "Model.hpp"
 #include "Point.hpp"
 #include "Print.hpp"
+#include "BeltTransform.hpp"
+
 #include "BoundingBox.hpp"
 #include "ClipperUtils.hpp"
 #include "Clipper2Utils.hpp"
@@ -13,6 +15,7 @@
 #include "PrintConfig.hpp"
 #include "SLA/IndexedMesh.hpp"
 #include "Support/SupportMaterial.hpp"
+#include "Support/SupportCommon.hpp"
 #include "Support/SupportSpotsGenerator.hpp"
 #include "Support/TreeSupport.hpp"
 #include "Surface.hpp"
@@ -987,6 +990,13 @@ void PrintObject::generate_support_material()
            this->_generate_support_material();
            m_print->throw_if_canceled();
        }
+        // Belt brim rides here rather than in the brim step because its apron
+        // prologue introduces print_z values below the object's first layer, and
+        // those must exist before ToolOrdering is built at psWipeTower - one step
+        // ahead of psSkirtBrim.  The brim options already invalidate
+        // posSupportMaterial, so this needs no extra invalidation edges.
+        make_belt_brim(*this);
+        m_print->throw_if_canceled();
        this->set_done(posSupportMaterial);
    }
 }
@@ -1080,7 +1090,10 @@ std::pair<FillAdaptive::OctreePtr, FillAdaptive::OctreePtr> PrintObject::prepare
    indexed_triangle_set mesh = this->model_object()->raw_indexed_triangle_set();
    // Rotate mesh and build octree on it with axis-aligned (standart base) cubes.
    auto to_octree = transform_to_octree().toRotationMatrix();
-    its_transform(mesh, to_octree * this->trafo_centered(), true);
+    // Overhangs below are placed at Layer::bottom_z(), which includes the belt global Z offset.
+    Transform3d object_trafo = this->trafo_sliced();
+    object_trafo.translation().z() += m_belt_global_z_offset;
+    its_transform(mesh, to_octree * object_trafo, true);

    // Triangulate internal bridging surfaces.
    std::vector<std::vector<Vec3d>> overhangs(std::max(surfaces_w_bottom_z.size(), size_t(1)));
@@ -1124,6 +1137,16 @@ void PrintObject::clear_layers()
        for (Layer *l : m_layers)
            delete l;
        m_layers.clear();
+        for (Layer *l : m_belt_truncated_layers)
+            delete l;
+        m_belt_truncated_layers.clear();
+        // Fills dropped for plastic saving are owned by the stash while they sit
+        // outside their layer's collection, so they are freed here too. Order
+        // matters only in that these point at layers deleted just above, and we
+        // never dereference the layer -- just the entity.
+        for (const BeltDroppedFill &d : m_belt_dropped_fills)
+            delete d.entity;
+        m_belt_dropped_fills.clear();
    }
 }

@@ -1157,6 +1180,101 @@ void PrintObject::clear_support_layers()
            l->cantilevers.clear();
        }
    }
+    // Belt brim is owned by the same step, so it must die with it or an
+    // invalidate-without-rerun would leave stale bands (and stale prologue Zs)
+    // behind.  Unconditional: unlike support layers it is never shared.
+    this->clear_belt_brim();
+}
+
+// Belt brim ------------------------------------------------------------------
+//
+// The tilt test is answered from the print CONFIG, not from SlicingParameters:
+// invalidating posSupportMaterial clears m_slicing_params.valid, and this is
+// queried from Print::process() dispatch, Brim.cpp and the G-code emitter, where
+// a stale zero shear factor would silently drop the brim.  BeltBrim.cpp itself
+// reads the real belt floor through BeltFloorContext, where the parameters are
+// guaranteed current.
+bool PrintObject::has_belt_brim() const
+{
+    if (! m_print->has_tilted_belt())
+        return false;
+    // The purge prism is sacrificial and sits at the plate's edge; its generator sets no_brim, and
+    // this keeps it brimless whatever its config says, so a brim on the parts never blocks purging.
+    if (m_config.belt_purge_tower_object.value)
+        return false;
+    if (! this->belt_brim_instances_compatible())
+        return false;
+    if (m_config.brim_type == btNoBrim)
+        return false;
+    // An inner-only brim has no leading/extra geometry: leading_brim_length and
+    // extra_brim_width both widen the OUTER ring, which btInnerOnly never emits, so it
+    // produces nothing unless brim_width itself is positive.  Every other brim type is
+    // satisfied by any one of the three widths.  Requiring the width here (instead of
+    // "any width") stops has_belt_brim() - and therefore Print::validate() - from
+    // rejecting the prime tower / spiral vase for a brim that would never be drawn.
+    if (m_config.brim_type == btInnerOnly) {
+        if (m_config.brim_width.value <= 0.)
+            return false;
+    } else if (m_config.brim_width.value <= 0. && m_config.leading_brim_length.value <= 0.
+               && m_config.extra_brim_width.value <= 0.) {
+        return false;
+    }
+    return ! this->has_raft();
+}
+
+unsigned int PrintObject::belt_brim_filament() const
+{
+    // 1-based, matching PrintRegion::outer_wall_filament_id and the raw values pushed
+    // into LayerTools::extruders in ToolOrdering::collect_extruders (the whole list is
+    // reindexed to 0-based later).  Lowest positive outer-wall filament over the
+    // printing regions; 1 when none is explicitly set.
+    unsigned int brim_filament = 0;
+    for (size_t i = 0; i < this->num_printing_regions(); ++ i) {
+        const unsigned int f = this->printing_region(i).config().outer_wall_filament_id.value;
+        if (f > 0 && (brim_filament == 0 || f < brim_filament))
+            brim_filament = f;
+    }
+    return brim_filament == 0 ? 1u : brim_filament;
+}
+
+bool PrintObject::belt_brim_instances_compatible() const
+{
+    // One set of bands is shared by every instance of this object, so they must all sit at
+    // the same height on the belt.  Moving an instance ALONG the belt axis changes its
+    // physical belt-floor Z and would put its brim at the wrong height; moving it ACROSS
+    // the belt does not, so side-by-side copies are fine.
+    //
+    // belt_force_separate() in PrintApply.cpp already gives one instance per PrintObject
+    // whenever a global belt flag is set, which the shipped belt profiles do - this only
+    // matters for configurations that do not.
+    if (m_instances.size() <= 1)
+        return true;
+    // From the config, not m_slicing_params: this runs while those can be stale. A tilt
+    // about Y runs the belt along X, any other tilt along Y (see compute_belt_height_and_floor).
+    const int    axis = m_print->config().belt_slice_rotation.value == BeltRotationAxis::Y ? 0 : 1;
+    const Point &ref  = m_instances.front().shift;
+    for (const PrintInstance &inst : m_instances) {
+        const coord_t along = axis == 0 ? inst.shift.x() - ref.x() : inst.shift.y() - ref.y();
+        if (std::abs(along) > SCALED_EPSILON)
+            return false;
+    }
+    return true;
+}
+
+void PrintObject::clear_belt_brim()
+{
+    m_belt_brim_by_layer.clear();
+    m_belt_brim_areas_by_layer.clear();
+    m_belt_brim_prologue.clear();
+}
+
+void PrintObject::set_belt_brim(std::vector<ExtrusionEntityCollection> &&by_layer,
+                                std::vector<ExPolygons>                &&areas,
+                                std::vector<BeltBrimBand>              &&prologue)
+{
+    m_belt_brim_by_layer       = std::move(by_layer);
+    m_belt_brim_areas_by_layer = std::move(areas);
+    m_belt_brim_prologue       = std::move(prologue);
 }

 std::shared_ptr<TreeSupportData> PrintObject::alloc_tree_support_preview_cache()
@@ -1199,6 +1317,8 @@ bool PrintObject::invalidate_state_by_config_options(
    bool invalidated = false;
    for (const t_config_option_key &opt_key : opt_keys) {
        if (   opt_key == "brim_width"
+            || opt_key == "leading_brim_length"
+            || opt_key == "extra_brim_width"
            || opt_key == "brim_object_gap"
            || opt_key == "brim_use_efc_outline"
            || opt_key == "brim_type"
@@ -1580,7 +1700,8 @@ bool PrintObject::invalidate_state_by_config_options(
        } else if (
               opt_key == "flush_into_infill"
            || opt_key == "flush_into_objects"
-            || opt_key == "flush_into_support") {
+            || opt_key == "flush_into_support"
+            || opt_key == "belt_purge_tower_object") {
            invalidated |= m_print->invalidate_step(psWipeTower);
            invalidated |= m_print->invalidate_step(psGCodeExport);
        } else {
@@ -1613,9 +1734,15 @@ bool PrintObject::invalidate_step(PrintObjectStep step)
 		invalidated |= this->invalidate_steps({ posPerimeters, posPrepareInfill, posInfill, posIroning, posContouring, posSupportMaterial, posSimplifyPath, posSimplifyInfill });
        invalidated |= m_print->invalidate_steps({ psSkirtBrim });
        m_slicing_params.valid = false;
+        // The exact belt_floor_z_shift is recomputed when slice() runs again.
+        m_belt_floor_z_shift_cache_valid = false;
    } else if (step == posSupportMaterial) {
        invalidated |= this->invalidate_steps({ posSimplifySupportPath });
        invalidated |= m_print->invalidate_steps({ psSkirtBrim });
+        // SlicingParameters depend on support config (enable_support /
+        // raft_layers / enforce_support_layers feed min/max layer height in
+        // Slicing.cpp), so invalidate them here.  The vertex-scan
+        // belt_floor_z_shift is preserved via m_belt_floor_z_shift_cached.
        m_slicing_params.valid = false;
    }

@@ -1636,6 +1763,7 @@ bool PrintObject::invalidate_all_steps()
    bool result = inherited_invalidated || print_invalidated;
 	// Then reset some of the depending values.
 	m_slicing_params.valid = false;
+	m_belt_floor_z_shift_cache_valid = false;
 	return result;
 }

@@ -3973,8 +4101,28 @@ void PrintObject::update_slicing_parameters()
 {
    // Orca: updated function call for XYZ shrinkage compensation
    if (!m_slicing_params.valid) {
-          m_slicing_params = SlicingParameters::create_from_config(this->print()->config(), m_config, this->model_object()->max_z(),
+          coordf_t object_height = this->model_object()->max_z();
+          BeltTransformPipeline::BeltFloorParams belt_floor;
+          const auto &pcfg = this->print()->config();
+          if (pcfg.belt_printer.value) {
+              BoundingBoxf3 bb = BeltTransformPipeline::remap_bbox(*this->model_object(), pcfg);
+              if (BeltTransformPipeline::has_preslice_remap(pcfg))
+                  object_height = bb.size().z();
+              auto hr = BeltTransformPipeline::compute_belt_height_and_floor(pcfg, bb, object_height);
+              object_height = hr.object_height;
+              belt_floor    = hr.floor_params;
+          }
+          m_slicing_params = SlicingParameters::create_from_config(pcfg, m_config, object_height,
                                                                   this->object_extruders(), this->print()->shrinkage_compensation());
+          // Populate belt floor parameters into slicing params for support clipping.
+          m_slicing_params.belt_floor_shear_factor = belt_floor.shear_factor;
+          m_slicing_params.belt_floor_from_axis    = belt_floor.from_axis;
+          m_slicing_params.belt_floor_z_shift     = belt_floor.z_shift;
+          // Prefer the vertex-scan z_shift over the bbox approximation when
+          // slice() has already produced one (e.g. this rebuild was triggered
+          // by a support-config change, which doesn't move the belt floor).
+          if (m_belt_floor_z_shift_cache_valid)
+              m_slicing_params.belt_floor_z_shift = m_belt_floor_z_shift_cached;
      }
 }

@@ -4015,9 +4163,24 @@ SlicingParameters PrintObject::slicing_parameters(const DynamicPrintConfig &full
    sort_remove_duplicates(object_extruders);
    //FIXME add painting extruders

-    if (object_max_z <= 0.f)
-        object_max_z = (float)model_object.raw_bounding_box().size().z();
-    return SlicingParameters::create_from_config(print_config, object_config, object_max_z, object_extruders, object_shrinkage_compensation);
+    BeltTransformPipeline::BeltFloorParams belt_floor;
+    if (object_max_z <= 0.f) {
+        BoundingBoxf3 bb = model_object.raw_bounding_box();
+        object_max_z = (float)bb.size().z();
+        if (print_config.belt_printer.value) {
+            bb = BeltTransformPipeline::remap_bbox(model_object, print_config);
+            if (BeltTransformPipeline::has_preslice_remap(print_config))
+                object_max_z = (float)bb.size().z();
+            auto hr = BeltTransformPipeline::compute_belt_height_and_floor(print_config, bb, object_max_z);
+            object_max_z = (float)hr.object_height;
+            belt_floor   = hr.floor_params;
+        }
+    }
+    SlicingParameters params = SlicingParameters::create_from_config(print_config, object_config, object_max_z, object_extruders, object_shrinkage_compensation);
+    params.belt_floor_shear_factor = belt_floor.shear_factor;
+    params.belt_floor_from_axis    = belt_floor.from_axis;
+    params.belt_floor_z_shift     = belt_floor.z_shift;
+    return params;
 }

 // returns 0-based indices of extruders used to print the object (without brim, support and other helper extrusions)
@@ -4537,6 +4700,25 @@ void PrintObject::_generate_support_material()
        PrintObjectSupportMaterial support_material(this, m_slicing_params);
        support_material.generate(*this);
    }
+    // Global Z offset for support layers:
+    // - Normal support: layers already inherit global_z_offset from object layers.
+    // - Non-organic tree support (slim/strong/hybrid): plan_layer_heights() reads
+    //   from globally-offset object layers, so support layers already have it.
+    // - Organic tree support: generate_tree_support_3D() computes its own Z values
+    //   independently and does NOT inherit the offset — apply it here.
+    // Belt floor polygon clipping for non-organic tree support is done inside
+    // draw_circles() before area_groups and toolpaths are built.
+    if (is_tree(m_config.support_type.value) && std::abs(m_belt_global_z_offset) > EPSILON) {
+        // Resolve effective support style (same logic as SupportParameters).
+        auto style = m_config.support_style.value;
+        if (style == smsDefault)
+            style = smsTreeOrganic;
+        if (style == smsTreeOrganic) {
+            for (SupportLayer *sl : m_support_layers)
+                sl->print_z += m_belt_global_z_offset;
+        }
+    }
+
 }

 // BBS
@@ -4886,6 +5068,7 @@ static void project_triangles_to_slabs(ConstLayerPtrsAdaptor layers, const index
 void PrintObject::project_and_append_custom_facets(
        bool seam, EnforcerBlockerType type, std::vector<Polygons>& out, std::vector<std::pair<Vec3f, Vec3f>>* vertical_points) const
 {
+    const Transform3d object_trafo = this->trafo_sliced();
    for (const ModelVolume* mv : this->model_object()->volumes)
        if (mv->is_model_part()) {
            const indexed_triangle_set custom_facets = seam
@@ -4894,12 +5077,12 @@ void PrintObject::project_and_append_custom_facets(
            if (! custom_facets.indices.empty()) {
                if (seam)
                    project_triangles_to_slabs(this->layers(), custom_facets,
-                        (this->trafo_centered() * mv->get_matrix()).cast<float>(),
+                        (object_trafo * mv->get_matrix()).cast<float>(),
                        seam, out);
                else {
                    std::vector<Polygons> projected;
                    // Support blockers or enforcers. Project downward facing painted areas upwards to their respective slicing plane.
-                    slice_mesh_slabs(custom_facets, zs_from_layers(this->layers()), this->trafo_centered() * mv->get_matrix(), nullptr, &projected, vertical_points, [](){});
+                    slice_mesh_slabs(custom_facets, zs_from_layers(this->layers()), object_trafo * mv->get_matrix(), nullptr, &projected, vertical_points, [](){});
                    // Merge these projections with the output, layer by layer.
                    assert(! projected.empty());
                    assert(out.empty() || out.size() == projected.size());
--- a/Show More
+++ b/Show More