Create and edit 3D meshes in Blender — primitives, hard-surface modeling, mesh operators, modifier stacks (Bevel, Subdivision, Boolean, Mirror, Array, Solidify), bmesh-level edits, retopology basics. Use whenever the user asks to "make/model/create/build a 3D object", "shape/sculpt this", "add a cub

MCP backend Use when: Any geometry creation, mesh edit, or modifier stack work in Blender. Not for wireframe → 3D conversion (use wireframe to 3d) and not for sculpting strokes (Blender's sculpt mode is gestural, not text driven). Before the first Blender call, read [../text to blender/references/mcp backends.md](../text to blender/references/mcp backends.md). Prefer official MCP for shared capabilities; preserve the selected backend for the whole task. Tool names in recipes are client/legacy examples: map them through that reference and its agent host guide. Blender Modeling Create geometry in Blender via natural language. You emit Python code that the Blender MCP executes; the patterns below cover the common 80%. Decision tree Code execution rules (recap) Each backend code execution call gets a fresh Python namespace. Re import everything; identify objects by bpy.data.objects['name'] . Always name objects with GEO prefix. Never leave Cube.027 . Print structured output back so you can parse results. Chunk long sequences into multiple calls. Recipes Critical: axis orientation for elongated objects For any elongated/asymmetric subject (sword blade, knife, bottle, plank, bone, screwdriver tip, etc.), three axes have different meaning : Long axis — the length of the object (78cm for a sword blade) Broad axis — the wider face axis, what's visible from the "useful" viewing angle (4.5cm for a blade — the flat side you'd lay on a table) Thin axis — the narrower cross section axis (0.8cm for a blade — the cutting edge) Always orient elongated objects so the broad axis faces the camera in hero shots. A sword viewed edge on (camera looking down the thin axis) renders as a thin pole and looks nothing like a sword. The recipes below use this convention: Convention X (left right of object's local space) Y (front back of object's local space) Z (up down) Sword blade thin (0.8cm) broad (4.5cm) long (78cm) — vertical Knife blade thin broad long — horizontal Plank thin broad long Bottle symmetric (radius) symmetric (radius) long (height) After building, rotate the object so the broad axis points roughly toward the camera. For a sword standing upright with camera in front (camera in Y direction): rotate the blade 90° around Z so its local Y (broad) → world X, then the broad face is visible from the camera's perspective. Critical: connecting parts smoothly (no visible seams) When assembling a multi part subject (sword = blade + guard + grip + pommel; chair = seat + back + 4 legs), separate primitives abutting at exactly aligned face boundaries leave visible seams even though the math says they touch. Worse — different shape primitives (cylinder grip into cube guard) produce obvious "cylinder on rectangle" boundaries. Two fixes, used together: 1. Overlap parts deeply at joins. Make adjacent primitives interpenetrate by 5–15mm at every connection. The hidden volume disappears inside the larger part, leaving no visible seam. The cylinder grip's top 1.5cm is inside the guard cube — not visible from outside, so the transition you see is just gold guard surface, no cylinder meeting rectangle artifact. 2. Apply shade smooth() to rounded parts (cylinders, spheres, organic shapes). Shaded flat cylinders show every facet boundary; smooth shaded ones look continuous. Cubes and beveled hard surface parts can stay shaded flat (or be partially smoothed via Auto Smooth on Blender 4.x; Blender 5.x removed Mesh.use auto smooth so use modifier based smoothing or per face flags). Anti pattern (visible seams): Correct (hidden seams via overlap): For a truly seamless join (high quality renders), Boolean Union the same material parts: e.g. Boolean Union pommel + grip into a single mesh would eliminate the seam entirely. But this only works when both parts use the same material. Critical: tapering to a point (for blade tips) Don't just scale the top vertices toward zero — that produces a "chiseled flat" tip. Pinch all top vertices to a single point and merge them: This produces a true geometric point. Without remove doubles , the four collapsed verts stay as four distinct points at the same coordinate — the tip looks visually pointed but is degenerate topology. Recipe 1 — Add a primitive with a clean name Replace primitive cube add with: plane , uv sphere , ico sphere , cylinder , cone , torus , monkey . Each takes appropriate arguments ( radius , depth , vertices , segments , subdivisions ). Recipe 2 — Hard surface stack (the "Bevel + SubSurf" pattern) Critical : Bevel before SubSurf. Reverse this and you get pinching artifacts. Recipe 3 — Edit mode operations (extrude, inset, loop cut) Recipe 4 — Boolean cut (drilling a hole) Recipe 5 — Mirror modifier (only model half) Place Mirror first in the stack (before Bevel/SubSurf). Recipe 6 — Array along curve (chains, fences, beads) Recipe 7 — Block out (rapid composition test) Recipe 8 — Cleanup after curve→mesh or boolean Modifier stack order (memorize this) Wrong order = artifacts. The single most common amateur mistake is SubSurf before Bevel. Common pitfalls Symptom Fix Default cube look Add Bevel (0.02m, 3 segments) and SubSurf Sharp pinch on round shapes Bevel before SubSurf, not after Black faces in render Recompute normals ( mesh.normals make consistent ) Boolean creates n gons Apply Bool, switch to Edit, fix to quads, then SubSurf Symmetry breaks Use Mirror modifier, not duplicate and flip Mesh has hidden interior faces Mesh → Clean Up → Delete Loose When to load references/overview.md Load when: The recipes here don't match the request (need bmesh level precision, custom ops) Topology requirements are stricter than usual (animation ready, game LODs) Performance matters (foreach set, batch ops needed) The user references operators not in the recipes The reference covers: bmesh.ops cookbook, all bpy.ops.mesh. operators worth knowing, hard surface workflow with MESHmachine style chamfering, retopology guidelines, mesh clean checklist. What this skill is NOT for Wireframe drawing → 3D model: use wireframe to 3d Sculpting strokes: Blender's sculpt mode is gestural; can't be driven well from text Sweep along path / lofting / curve driven shapes: covered in wireframe to 3d/references/blender patterns.md Materials / lighting / rendering: redirect to those skills

blender-modeling