Whether you designed the part yourself or downloaded it from Printables, Thingiverse or MakerWorld, a few quick checks before you order make the difference between a perfect print and a frustrating one. Here are the seven we see most often.
1. Export in millimetres
STL files don't store units, just numbers. Most printers and slicers read those numbers as millimetres. If you designed in inches or centimetres, your part can come out 25 times too small or 10 times too big. Export in millimetres, and check the size readout after you upload. Our upload page shows the model's size straight away and warns you if it looks suspiciously tiny.
2. Make sure the model is watertight
A printable model needs a closed surface with no gaps, like a balloon with no holes. Models with open edges, flipped faces or overlapping parts can print with missing sections. Most CAD programs export watertight files. For downloaded or sculpted models, free tools like Microsoft 3D Builder, Meshmixer or the repair button in Bambu Studio or PrusaSlicer can fix common problems.
3. Check your wall thickness
Very thin walls print weak or not at all. As a rule of thumb, keep walls at least 1.2 mm thick, and 2 mm or more for parts that take any load. Thin pins and tabs under about 2 mm across can snap.
4. Watch out for overhangs
Printers build upward one layer at a time, so surfaces that hang out over thin air need support. Overhangs up to about 45 degrees usually print fine. Steeper overhangs and flat ceilings need supports, which leave marks where they're removed. Chamfers instead of flat undersides, or splitting a part into pieces, often give a cleaner result.
5. Don't go too small on details
Very fine text, sharp points and hairline features can disappear. Raised or engraved text should be at least about 0.5 mm deep and 2 mm tall for clean results.
6. Leave clearance for parts that fit together
If two printed parts need to slide or snap together, leave a gap between them, usually 0.2 to 0.4 mm. Holes often print slightly smaller than designed, so add a little extra for screws and pins.
7. Think about orientation and strength
3D printed parts are strongest along their layers and weakest between them. If a part will be bent or loaded, tell us which direction the force goes, and we'll orient it for strength. Add it in the notes when you order.
File types we accept
- STL and OBJ: instant price, live 3D preview and coloring on our custom print page.
- 3MF and STEP: send them through Get a Quote and we'll price them by hand.
Not sure about your file?
We check every file before printing. If something needs fixing, we contact you first. Not sure which material to choose? See PLA vs PETG vs TPU. Wondering about price? Read how much 3D printing costs.