How to prepare an STL file for 3D printing

Half the delays in 3D printing come from file problems that take two minutes to prevent. Follow these five checks and your part goes straight from inbox to print bed.

1. Export in millimetres

The most common problem we see: a file designed in inches or metres arrives 25× too small or 1000× too big. Every CAD tool (Fusion 360, SolidWorks, Tinkercad, Blender) lets you set export units — set them to millimetres. If unsure, tell us one known dimension ("this hole should be 5 mm") and we'll verify the scale.

2. Make sure the model is watertight

A printable model must be "manifold" — a fully closed surface with no holes, gaps or zero-thickness walls. Free tools fix most issues automatically: the built-in repair in Cura or PrusaSlicer, or Microsoft's free 3D Builder on Windows. If the slicer preview shows missing chunks, the file needs repair.

3. Respect minimum wall thickness

FDM printing has a physical floor: a 0.4 mm nozzle can't produce a reliable 0.3 mm wall. Practical minimums:

• Walls: 1.2 mm minimum, 2 mm for anything structural
• Embossed text/logos: 0.6 mm deep, 5 mm tall to stay readable
• Pins and thin posts: 3 mm diameter or they'll snap
• Holes for screws: add 0.2–0.3 mm clearance over the bolt size

4. Think about orientation (or let us)

Layer lines are the grain of the wood: a part is strongest along layers and weakest between them. A hook printed upright snaps at the curve; printed flat, it holds. You don't have to solve this yourself — mention how the part will be loaded and we orient it for strength.

5. Name and send it properly

Send STL, STEP, 3MF or OBJ directly on WhatsApp or email — not a screenshot, and not embedded in a Word document (it happens more than you'd think). If you have multiple parts, one file per part named clearly: bracket-left-v2.stl beats final-FINAL-2.stl every time.

No CAD file at all?

That's fine. We build printable models from hand sketches, photos with measurements, or the broken original part — CAD modelling starts at ₹250. Details on the custom parts service.