Mesh to a STEP solid
A mesh is a skin of triangles; CAD wants a solid made of faces it can select, offset and fillet. ShapeMason merges the triangles of each flat area into one face and writes a STEP solid. With Prismatic conversion, faceted holes and bosses become true cylinders.
fixtures/examples/bracket.stl with Prismatic conversion: 226 triangles
become 15 faces, the hole one cylinder.
Open the mesh and choose Mesh to Solid (STEP) (the default for meshes), or Split to Bodies (STEP) for one file per part.
shapemason mesh-to-solid bracket.stl # or just: shapemason bracket.stlshapemason mesh-to-solid --prismatic bracket.stlshapemason split assembly.3mf # one STEP per partFormats
Section titled “Formats”| Format | Read |
|---|---|
| STL | ASCII and binary. No units: read as mm |
| 3MF | Build items, transforms, units and colors; Bambu Studio’s separate model parts; support and modifier objects skipped |
| OBJ | One body per object |
| PLY | |
| glTF, GLB | Node transforms and base color; Y-up, turned Z-up |
fixtures/examples/plate.3mf: the 3MF’s own unit and placement are kept.
Before converting
Section titled “Before converting”Analyze shows what’s in the file: each object’s triangles, shells, whether it is watertight, its size and volume. In the app and web app it’s in the report (Analysis); on the CLI:
shapemason analyze bracket.stlA solid needs a watertight mesh: every edge shared by exactly two triangles. If it isn’t, conversion stops; see the mesh is not watertight.
Options that matter most
Section titled “Options that matter most”| You want | Use |
|---|---|
| Real cylindrical holes, bosses and straight fillets | Prismatic conversion (--prismatic) |
| The right size | Units (--units): 3MF says; STL has none, so mm is assumed |
| Z up from a Blender or game asset | Up axis › Y (--up y); glTF is Y-up already |
| The part sitting on the origin | Origin › Bottom center (--origin bottom-center) |
| One object of several | Object (--object NAME); Analyze lists them |
| A broken mesh fixed first | Repair mesh (--repair) |
Separate shells become separate solids in one file, or with Split to Bodies one file each, named after the part. Every option: Meshes.
Curved surfaces
Section titled “Curved surfaces”Without Prismatic conversion, curved surfaces stay faceted: one flat face per facet. Booleans still work, and CAD can be slow with many faces (over 5,000 gets a warning). Prismatic conversion recognizes cylinders today; cones, spheres and tori aren’t recognized yet, and neither are cylinders whose ends aren’t square to their axis.
Use cases
Section titled “Use cases”Editing downloaded parts, broken meshes, game assets, scans, one object of many, noisy faces, wrong units: step by step, for every front end.