Top 10 beginner mistakes (and how to dodge them)
Every mistake on this list has cost makers a wasted print. Catch them in CAD instead.
The top ten
1. Walls too thin. Anything under 1.6 mm probably won't survive printing. See Wall thickness.
2. Holes too tight. Holes shrink. Always add 0.15-0.4 mm clearance. See Tolerances.
3. Designing supports. The slicer adds them. You model the part you want; the slicer figures out scaffolding.
4. Printing the part standing up. Big flat face goes on the plate. Tall parts wobble, take longer, and fail more.
5. Sharp overhangs. A face that points more than 45° below horizontal needs supports OR a 45° chamfer in CAD. Add the chamfer.
6. Not checking the dimensions. A 1 cm phone stand is useless. ForgeSlicer's bottom-bar shows mm at all times — read it before saving.
7. Forgetting to mark holes as Negative. A positive cylinder makes a peg; a Negative cylinder makes a hole. ForgeSlicer's modifier toggle is one click on the primitive.
8. Printing without a brim on small bases. Slicer setting, not CAD — but worth knowing: anything with a footprint smaller than ≈ 20×20 mm gets a brim. It pops off after.
9. Exporting STL when you needed 3MF. STL loses your part hierarchy (positives + negatives collapse into one mesh). For OrcaSlicer / Bambu Studio / PrusaSlicer, prefer 3MF.
10. Not test-printing a tiny version. A 10-minute scaled-down print catches 90% of design issues. Cheaper than a 4-hour failed full print.
If you only remember three
Walls ≥ 1.6 mm. Holes need clearance. Big flat face on the plate. Get those three right and you'll print successfully on your first try.
Most failed first prints are one of ten predictable design choices — and ForgeSlicer flags eight of them in the workspace before you slice.