3MF: 3MF (3D Manufacturing Format) is a modern 3D printing file format that stores a mesh together with units, colours, materials and multiple objects in a single compressed file.
3MF was created by an industry group, the 3MF Consortium, to replace STL for 3D printing. It is a ZIP archive containing XML that describes one or more meshes, plus the information STL leaves out.
The most useful differences in practice:
- units are recorded, so a part designed in inches does not arrive 25.4 times too small;
- several parts, with their positions, can travel in one file;
- colours, materials and textures can be attached to the geometry;
- slicer settings and print plates can be stored alongside the model;
- the format is compressed, so files are usually much smaller than an equivalent STL.
Example: a buyer exports a two-part enclosure from CAD as a single 3MF. The shop opens it and sees both parts, correctly sized in millimetres, already arranged on a plate. The same export as STL would be two files with no units.
3MF is still a mesh format. It does not store the exact surfaces of a STEP file, so it is not the right choice for CNC machining. And like any mesh, a 3MF can still contain holes or overlapping faces if the export was poor.
Support for 3MF is now broad among slicers and CAD tools, though some older software still only reads STL. Read STL vs STEP vs 3MF for which to ask your buyers for.
Go deeper: STL vs STEP vs 3MF (and OBJ, DXF, IGES): which file to send for a quote