Design for the process, not against it
Most failed prints are not machine problems. They are geometry that was drawn without thinking about how it would be built. These are the seven checks we run on every incoming model.
1. Respect the 45 degree rule
Overhangs shallower than about 45 degrees from vertical print unsupported. Steeper than that and you need support material, which means scarring on the supported face. Chamfers instead of fillets on downward-facing edges will often remove the need entirely.
2. Give holes somewhere to go
Horizontal holes print as slight ovals because the top arch has to bridge. If a hole is critical, either orient it vertically or draw it as a teardrop so the top self-supports. Better still, print it undersize and drill it.
3. Wall thickness is not decorative
Below about 0.8 mm on FDM, a wall becomes a single extrusion with no internal bonding and snaps easily. Below 0.4 mm the slicer may skip it entirely. On resin, 1 mm is a sensible floor for anything that will be handled.
4. Plan tolerances, do not hope for them
For a part that must slide, allow 0.3 mm of clearance. For a press fit, 0.1 mm of interference. For threads, print the male and tap the female. These numbers are process-specific and worth testing once with a small gauge print.
5. Fillet the base
A sharp 90 degree transition to the build plate concentrates stress exactly where warping pulls hardest. A 1 mm fillet at the base costs nothing and prevents a whole class of corner lift.
6. Split large parts deliberately
If a model exceeds the build volume, decide the split yourself rather than letting someone else guess. Cut along a plane that hides in the design, add interlocking keys so assembly self-aligns, and you will get a seam that disappears under filler.
7. Send the file with units
Half of all scaling errors are a millimetre model interpreted as inches. STEP and 3MF carry units unambiguously. If you send STL, tell us the intended overall dimension in the message.