cgs-mold

name	cgs-mold
description	Turn a gun scan into a handoff-ready custom-gear.ch (René Spatz) holster split-mold, fully inside Blender via blender-mcp. Use when the owner says "make a mold from this scan", "cgs-mold", "turn <gun> scan into a mold", or provides a gun scan + active Blender MCP and asks for a holster mold. Blender-only — no FreeCAD.
triggers	["cgs-mold","/cgs-mold","holster mold","gun scan to mold","make a mold from this scan","turn this scan into a mold"]

cgs-mold — gun scan → holster split-mold (Blender-only)

Pipeline that reproduces René Spatz's custom-gear.ch holster blocking inside Blender, driven over blender-mcp. Input: a gun-scan mesh already in the Blender file (or an STL to import) + the MCP server live. Output: a cut, smoothed, offset mold object ready for STL export + handoff.

★ SOURCE OF TRUTH = METHOD-NOTES.md. It holds the live, owner-validated gun-dip method + the root-cause findings. The pipeline below is the current method; the OLD heightfield-sweep / hammer-cut pipeline is superseded (kept only in git history).

Failure-anchored rules (verified 2026-06-29/30):

1. Never round the SCAN's detail (no voxel/marching-cubes to retopo the scan surface — it washes the sharp swept edges; the recurring 2026-06-28 failure).
2. The mold MUST be a FILLED SOLID before any boolean cut. A swept mold often comes out as a closed shell with internal walls (nonmanifold>0 with boundary==0). A boolean can't read inside-vs-outside through internal walls → it tears / empties / leaves the cut piece. Fix = voxel-remesh the MOLD (not the scan) into one filled solid (manifold 0/0, single island), THEN cut. Detail softened by the fill is recovered by the feature-preserving smooth (step 4).

Pipeline (owner gun-dip method — validated)

1. Swept solid (the dip) — gun-solid drawn continuously along the draw axis (+Y) through a block carves a continuous cavity; invert + solidify → the swept-gun positive = the mold. No stepping (union-of-copies = steps = rejected).
2. Solidify / fill — voxel-remesh the mold into ONE filled solid (manifold 0/0, single island, bbox preserved). This is the precondition for a clean cut (see failure-rule 2). [VALIDATED]
3. Grip cut — separate CUBE cutter, BOOLEAN DIFFERENCE, solver='FLOAT' on the solid (EXACT empties on heavy voxel meshes). Diagonal plane through two owner-set points: first = trigger-guard/grip corner, corner_below_mm (20) BELOW; second = beavertail, beavertail_below_mm (10) BELOW. Cube top face on that line, body on the grip side; delete cube. [VALIDATED]
4. Smooth / retouch (smooth_mold) — feature-preserving denoise of the voxel surface; smooth AND sharp (keeps edges, bevels, grooves, corners crisp, no global rounding). 4 sub-passes: flat Taubin denoise (sharp creases frozen) → crease-line de-zigzag (1D midpoint along the crease, corners frozen — this is what makes a jagged edge smooth and still sharp) → roughness deburr (melt voxel stair-steps by Laplacian magnitude, topology-agnostic) → crease re-straighten. [VALIDATED] 4b. Overhang cleanup (remove_overhang) — strong local collapse of any stray flap/hook "hanging over" the cut edge (e.g. the beavertail remnant). Gentle smoothing won't shift a flap; a tight high-iteration local Laplacian pulls it flush while the flat cut verts hold. [VALIDATED]
5. Offset +0.4 mm — SLIDE REGION ONLY (offset_mold) — owner corrected (2026-06-30): the +0.4mm Kydex-shrink comp goes on the barrel + slide + beavertail only (the top assembly above the slide/frame parting line, z_line≈14mm), NOT everywhere — the grip/frame/trigger guard stay put. Push the region verts outward along normals, feathered ~2mm at the line (no ridge). Verify the region bbox grew outward (else normals were inward). [VALIDATED]
6. Split into clamshell halves (split_mold) — owner spec (2026-06-30): a clean SPLIT, NOT a material-removing saw cut. bisect_plane + holes_fill on each side → two capped, closed, manifold halves that together reconstitute the whole mold (verified 0.006% volume loss = float noise). The seam is a VERTICAL plane through the — circle-fit the muzzle crown (), NOT the mold symmetry plane/centroid (one-sided controls pull that off the bore; "center of the barrel, not the centre of the entire mold"). [VALIDATED]

Invocation (blender-mcp must be live on :9876)

Run the engine inside Blender via execute_blender_code; it execs the on-disk module so the heavy logic stays version-controlled:

import json
exec(open("/Users/marcelspatz/YURI-OS-MUSUBI/.claude/skills/cgs-mold/scripts/cgs_mold.py").read(), globals())
params = json.load(open("/Users/marcelspatz/YURI-OS-MUSUBI/.claude/skills/cgs-mold/params/hk45.json"))
build_mold("<MOLD_SHELL_OBJECT>", params)   # solidify -> cut -> 4-stage smooth; never edits the input

build_mold runs the validated CORE (solidify → cut → smooth) on a swept-mold shell object. The stages are also callable individually — solidify_mold, cut_grip, smooth_mold, remove_overhang — so the owner can tune one stage and render between. Each returns (object, summary_dict) and is non-destructive (every stage builds a NEW object). build_mold writes /tmp/cgs_mold_summary.json.

Verify by rendering the result object after each stage (bpy.ops.render.opengl(view_context=True) to a PNG, then Read it). The owner's eye sets cut placement + smooth strength — don't trust counts alone.

Parameters (per-gun preset JSON in params/)

• solidify.voxel_size (0.7) — voxel-fill resolution; finer = less stepping, heavier mesh.
• grip_cut: solver (FLOAT), corner_below_mm (20), beavertail_below_mm (10) — the two cut points.
• smooth (optional overrides) — feature_angle (50), pass counts, deburr_thr; defaults are baked into smooth_mold.
• out_name, render.

Cut points are auto-detected then tuned visually per scan — _find_cut_points locates the trigger-guard/grip corner (knee of the bottom-Z profile) + the beavertail (rearmost mid-height vert), the owner's eye sets the final *_below_mm. New gun → copy hk45.json, adjust the two offsets.

Safety conventions (born from 2026-06-28)

• Non-destructive: reads only the scan's verts; the source object is never mutated; every run creates a NEW object and hides the scan. No in-place edits, no booleans on the scan.
• Render-verify every run before claiming done; tune against the PNG, don't trust counts.
• If a mesh op would mutate existing geometry, snapshot/duplicate first.

Status / scope

• VALIDATED (owner-confirmed 2026-06-30, "this is successful"): solidify (voxel-fill) → grip cut (FLOAT cube DIFFERENCE, corner−20/beavertail−10) → 4-stage feature-preserving smooth → overhang cleanup. Manifold 0/0 throughout. Deliverable on HK45 = CGS_MOLD_FINAL.
• TODO: +0.4mm offset, un-subdivide/decimate, X/Y split into clamshell halves + alignment pins, STL export gate.
• Upstream not re-validated this session: the seal→dip/sweep stages that produce the mold shell (this run started from a pre-existing swept shell). Those need their own validation pass + functions.

Session Notes

2026-07-06

• session: 54m | peak ctx: 0% | compacts: 0
• tools: Bash×601, Read×198, Edit×56, WebFetch×28, Write×17, Agent×13, WebSearch×9, StructuredOutput×9, ToolSearch×8, mcp×2, ReportFindings×2, TaskList×1, TaskOutput×1, Workflow×1, CronCreate×1
• corrections: none
• errors: none

2026-06-30

• session: 1167m | peak ctx: 0% | compacts: 0
• tools: Read×2267, Shell×951, Grep×328, Write×271, mcp×54, Bash×38, Edit×18
• corrections: that was successful, we need to clean the back face up before we continue otherwise we will run into issues again.
• errors: none