3MF packages a model and related information in a ZIP-based document structure. Core model objects contain geometry, while build items identify what is placed in the build. The broader format can carry appearance and manufacturing information that a plain triangle file cannot express.
- Geometry
- Core mesh resources can be referenced by build items. Component structures and extensions go beyond this workbench’s supported subset.
- Units
- Model length units are declared; the core format defines millimetres when the unit attribute is absent.
- Appearance
- Color, material and other resource data may be present. Geometry-only conversion does not retain them.
- Placement
- Build transforms place geometry; reading only raw mesh vertices can lose that placement.
Keep the original package when settings matter
3MF→STL is useful for geometry exchange with a mesh-only application. It is not a substitute for preserving a slicer project or manufacturing package. Retain the original 3MF if build configuration, object structure or metadata will be needed later.
STL and OBJ exports use millimetre coordinates
The local reader applies the supported build transforms and unit conversion before export. STL merges the placed triangles, while OBJ keeps geometry groups. Neither output retains the full package semantics. Select mm in the receiving application because these outputs do not enforce equivalent unit metadata.