File formats
3MF
3D Manufacturing Format
Definition
3MF is an XML-based file format for additive manufacturing maintained by the 3MF Consortium. Unlike STL it can carry units, colors, materials, and multiple objects in one package, but its geometry is still a triangle mesh, not editable CAD geometry.
Also known as: 3D Manufacturing Format, .3mf
Updated
Why printers moved to it#
3MF packages the model and its print-related data together, so a slicer receives units, colors, materials, and several objects in one file instead of a bare triangle list.
Stricter meshes#
The 3MF Core Specification requires model meshes to have manifold edges and consistent triangle orientation. That makes a valid 3MF more likely to slice cleanly than an arbitrary STL. It does not make 3MF a CAD exchange format: for design edits, use STEP.
Sources
Related terms
STL
STL is a simple mesh file format that stores a surface as a list of triangles, each with a normal and three vertices. It is the long-standing default for 3D printing, but it has no units, colors, or exact geometry.
Mesh
A mesh represents a shape as a surface of small flat polygons, almost always triangles, joined at shared edges and vertices. Meshes work well for rendering, games, and 3D printing, but they have no true faces, edges, or exact curves, so they are hard to dimension or edit as engineering geometry.
Manifold
A manifold mesh is one where every edge is shared by exactly two triangles, so the surface clearly separates inside from outside. Slicers, mesh booleans, and CAD imports rely on manifold geometry to behave predictably.