File requirements
Formats we take
STL: the default for 3D printing. Triangles only, no units, no colour. Export in millimetres.
OBJ: geometry plus optional material references. We use the geometry.
3MF: the modern one. Carries units, so there's no scale ambiguity. Use it if your software offers it.
STEP: solid CAD geometry rather than a mesh. Converted in your browser. Fine for parts from Fusion, SolidWorks or Onshape.
Maximum 100 MB per file. One part per file.
What we don't take
No G-code: that's sliced for one specific machine and one specific material, and it won't be the maker's. No project files (.f3d, .sldprt, .ipt). No ZIP archives. Export a mesh or a STEP.
Getting the export right
Units. STL and OBJ carry no units, so a part exported in centimetres arrives ten times too big. Check the size we show after upload against what you designed. If it's out by a factor of 10 or 25.4, that's your unit setting.
Resolution. Most software has a tolerance or deviation setting on export. 0.01 mm is plenty. Going finer just makes a huge file that's slow to load and prints identically.
Watertight. The mesh should be closed: no holes, no flipped faces, no edges shared by more than two triangles. We tell you when it isn't. Most slicers repair small problems, but a mesh with real holes can slice into something that isn't your part.
Orientation. Put the flattest face down, in Z, if you have a preference. Makers usually re-orient for a better print, so tell them in the notes if orientation matters: for example if a surface has to be smooth or a feature has to be strong along one axis.
Size limits
Every printer has a build volume. If your part is bigger than a maker's, they can't print it whole. Under 200 × 200 × 200 mm fits nearly every machine on PrintFlows. Above 300 mm on any side, the pool of makers gets thin fast.
Too big? Split it into pieces and glue or bolt them together. Say so in your notes and a maker will often suggest where to cut.
Small features that don't survive
- Walls under 0.8 mm may not print at all, or snap when handled.
- Text under 3 mm tall comes out mushy. Embossed reads better than engraved.
- Holes under 2 mm print undersized. Design them oversized, or ask the maker to drill them.
- Pins and posts under 2 mm break on removal from the bed.
Fixing a broken mesh
Free options: Microsoft 3D Builder (Windows, has a repair button), Meshmixer, Blender's 3D-Print Toolbox, or the Netfabb service built into most slicers. Re-export after repairing and upload again.