Sculpt Models

This craft skill owns digital sculpting: form, anatomy, surface detail, environment sculpts and the Blender 5.x sculpt toolset, through to a retopologised and baked asset. It is called by 3d-generalist and model-characters. Read local.md next to this file when it exists (machine paths).

When to use

• A character, creature, head or bust that must read as organic, not blobby or symmetric.
• Rocks, cliffs, terrain, bark, ruins, worn and damaged props.
• Refining an AI base mesh (Tripo Studio) or a scanned mesh: re-cutting planes, eyelids, mouth corners, folds.
• A realistic close-up asset from AI: generate in parts, retopo, bake to a low poly (references/ai-mesh-to-game-ready.md).
• Turning one picture (AI image, render, figurine photo, drawing) into a sculpt measured against it.
• Baking sculpt detail onto a low-poly mesh for a game engine, three.js or 67js.

Not this skill: stylised cartoon character sculpts step by step (~/.claude/skills/model-characters/references/sculpt-stylized.md), machined parts at exact dimensions (model-parts-in-cad), drawing anatomy in 2D (draw-and-paint-art).

Order of work

1. Reference first. Real photos or scans of the subject from several views (the real resources first rule): an animal, a rock type, a face type. Never sculpt a real thing from memory.
2. Decide the end state. Static (prop, environment, still) or deforming (rigged, animated); target face count and where it ships (references/blender-sculpt-tools.md, "Retopology and bake"). This decides every later step.
3. Block out primary forms from simple volumes at real scale, symmetry on, 5k to 20k faces, Voxel Remesh to unify. Run scripts/check_sculpt.py and read the silhouette sheet before any detail.
4. Secondary forms: planes, landmarks, muscle groups, folds, fracture planes (references/form-and-anatomy.md, references/surfaces-environment-and-hard-surface.md).
5. Break symmetry for anything alive, then Multires for tertiary detail in distinct layers by scale.
6. Retopologise or decimate, then bake normals (and displacement where detail changes the silhouette).
7. Check again (below) at the final camera distance, then hand the asset to rig-characters or the scene.

Hard rules

• Big to small, always. No detail on a form whose silhouette has not passed.
• No global noise displace on a primitive as "sculpting": masses are built as volumes first.
• No perfect mirror on anything alive; no random vertex jitter as "asymmetry".
• Detail comes in distinct scales with rest areas between; one-frequency noise everywhere fails.
• Eyes, lids, lips, ears and nostrils have thickness and structure (references/form-and-anatomy.md §2).
• A sculpt that must deform is retopologised; a static one may be decimated. Never rig raw Dyntopo or voxel topology.
• Apply scale before sculpting; a scaled object stretches every stroke.

Check gate (run before showing anyone)

blender -b <file.blend> --python scripts/check_sculpt.py -- [--object Name] [--out <folder>]
blender -b --python scripts/check_sculpt.py -- --import model.glb --out <folder>

It prints faces, scale, non-manifold edges, loose vertices, mirror error and surface busyness, and writes a silhouette sheet (8 angles plus top and bottom) and a matcap and studio sheet. Exit 1 means a measured check failed. Then look (more than about 5 pictures go through a frame-reading subagent):

1. The silhouette reads as the subject from every angle, at thumbnail size.
2. Under the raking studio light, forms are planes and landmarks, not mush; nothing is lumpy noise.
3. Squint: only primary and secondary forms remain, with a clear value pattern.
4. Flip the front view horizontally: proportion and tilt errors pop out.
5. At the final output size, delete detail nobody will see; keep what reads.

Tests: bash tests/test_check_sculpt.sh (a clean fixture passes, a broken one fails on scale and a loose vertex). Worked procedural example: blender -b --python scripts/procedural_rock.py -- --out rock.blend (joint-set cuts, corner chips, masked layered displacement, QuadriFlow or Decimate low copy).

References