Export STL from CAD
A good print starts with a good file. Most files from ready-made model libraries like MakerWorld or Printables are already good enough to print as they are. If a model is brand new or has few reviews it can be worth checking it against the points below. If you make your own models in CAD and want them printed, this guide shows how to export a watertight STL or STEP from the most common programs, with the right resolution and unit.
STL or STEP?
STL describes the surface as triangles and is the standard for 3D printing. STEP keeps the exact geometry and is preferable if you want us to be able to adjust or measure the part. We accept STL, STEP and 3MF. Upload STEP if you have it.
Correct resolution
When exporting STL you control accuracy with two values: chord tolerance (how far the surface may deviate) and angular tolerance. Set chord tolerance around 0.01-0.05 mm for printed parts. A lower value gives smooth curves without an unnecessarily large file.
Too coarse and the triangles show as facets on round surfaces; too fine and the file is needlessly heavy with no visible gain.
Per program
Fusion 360: right-click the body → Save As Mesh → STL, choose High refinement. SolidWorks: Save As → STL → Options, set Resolution to Fine or a custom tolerance. Onshape: right-click Part → Export → STL, Fine. FreeCAD: select the body → File → Export → STL, set deviation low. Tinkercad: Export → STL.
Check before you upload
Make sure the model is a closed volume (watertight), in millimetres and at 1:1 scale. Thin walls should be at least 0.42 mm. A part with open surfaces or the wrong unit cannot be printed correctly.
If unsure, upload the file anyway. We review the geometry and get back to you if something needs adjusting before production.
FAQ
- Which file format should I send?
- STL, STEP or 3MF all work. Prefer STEP if you have it. It preserves the geometry and makes it easiest for us to change the file if needed.
- Which unit should the model be in?
- Millimetres at 1:1 scale. The wrong unit is the most common reason a part comes out the wrong size. You can check your model's dimensions in the 3D viewer by selecting the bounding box to verify they match your requirements.
- What if my file is not watertight?
- Run an automated repair on the file first. If the automatic tool gives a poor result we also do a manual repair. Upload the file anyway, we review the geometry and come back before printing. Repair your STL online