3MF file: what it is and why it is better for colour printing

What is inside a 3MF file

The 3MF format was introduced in 2015 by a consortium of companies around Microsoft, and is now run by the 3MF Consortium. Inside, it is an ordinary ZIP archive of text files in XML. The model is stored much as in STL, as a mesh of triangles.

The difference is everything else a 3MF remembers. It always knows the numbers are in millimetres, and it carries the colours of the individual parts, their names and their arrangement. If you save it from a slicer as a project, the print settings are in there too. The consortium publishes the full specification for free.

When to send 3MF instead of STL

If you want a part in several colours, send a 3MF. The colours you assigned in your program stay exactly as you set them, and we do not have to fill them in by hand. We can print up to 4 colours on one part, and you can read more in the multicolour printing entry.

3MF is also worth using for a single-colour part when you are not sure about the units. The model will not upload ten times too small or too large, because the millimetres are written into the file.

What to watch out for with 3MF

• You choose the material and strength with us. If a different material or infill is saved in the 3MF, we use whatever you pick in the calculator. We print in PLA and PETG, with 10, 15 or 40% infill.
• Several parts in one file. Each part has to fit within 246 × 246 × 256 mm. A larger model has to be split into pieces.
• File size. A project with all its settings and previews is usually bigger than the model alone. We accept files up to 50 MB.

How a 3MF turns into a price

After you upload, we really do prepare the model for printing on our server, in a slicer based on OrcaSlicer. We find out exactly how many grams of material and how much print time the part needs. The price per piece and the delivery date come from that, not from an estimate based on volume.