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STEP, STL or 3MF — which file do you actually want?

Every model here ships in more than one format. A short guide to what each one is good for, so you download the right thing the first time.

3d-printingfiles

Most parts on the downloads page are published in more than one format. That is deliberate — the three do genuinely different jobs — but it does mean picking one. Here is the short version.

STEP — the editable source

A STEP file carries the actual geometry: real curves, real planes, real dimensions. Open it in Fusion, FreeCAD, SolidWorks or Onshape and you can change a hole diameter, thicken a wall, or cut the part in half without fighting a mesh.

Download STEP when you want to modify the part, adapt it to different hardware, or use it as a reference for something of your own.

The trade-off is that a STEP is not directly printable. Your slicer wants a mesh, so you would export one from it anyway.

STL — the print-ready mesh

An STL is the part flattened into triangles. Nothing else: no units baked in, no colours, no per-part settings. Every slicer on earth reads it, which is exactly why it is still the default after forty years.

Download STL when you just want to print the part as designed.

The trade-off is that it is very hard to meaningfully edit. A curve that was a smooth arc in CAD is a few hundred flat facets in an STL, and editing it means mesh surgery rather than changing a dimension.

3MF — the whole print, arranged

A 3MF is a container. It can hold several parts already positioned on the plate, with their orientation, colours and per-object settings intact — and in most modern slicers it carries the project settings too.

Download 3MF when there is a multi-part assembly and you would rather not work out the plate layout yourself, or when a part needs specific settings to print correctly.

The trade-off is portability: how much of the arrangement survives depends on the slicer opening it.

The rule of thumb

  • Printing it as-is → 3MF if one exists, otherwise STL.
  • Changing anything → STEP.
  • Not sure → grab the STL, print it, then come back for the STEP if you want it different.

Everything is on the downloads page, filterable by format, and free either way.

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