tutorials
Preparing Your 3D Model for Printing
Nothing's worse than waiting for a print only to find out there was an issue with the model. Here are the most common problems I see—and how to fix them before you upload.
Check Your Wall Thickness
This is the #1 cause of failed prints. Walls that are too thin either won't print at all or will be incredibly fragile.
The rule: Keep walls at least 1.2mm thick. For functional parts, 2mm+ is better.
Most CAD programs can analyze wall thickness. In Fusion 360, use the "Inspect" tool. In Blender, you can use the "3D Print Toolbox" addon.
Make Sure It's Watertight
A "watertight" mesh means the model is completely closed—no holes, no gaps. Think of it like a balloon: if you filled it with water, would it leak?
Common causes of non-watertight meshes:
- Flipped normals (faces pointing the wrong way)
- Overlapping geometry
- Gaps between surfaces that look closed but aren't
Quick fix: Most slicing software can repair minor issues automatically, but major problems need to be fixed in your design software. Meshmixer (free from Autodesk) is great for repairs.
Watch Your Overhangs
3D printers build layer by layer from the bottom up. That means anything that sticks out more than 45° from vertical needs support material underneath.
Options:
- Design self-supporting geometry when possible
- Orient the part to minimize overhangs
- Accept that supports will be needed (we handle this during slicing)
Supports leave marks where they attach, so think about which surfaces matter most for your part.
Real Example: Custom Keycaps for Mintlify
When Mintlify needed custom keycaps, the design had to be precise. Keycaps have tight tolerances—too thick and they won't fit, too thin and they'll break.
Custom keycaps with precise wall thickness and detailed features
The key to success? Proper wall thickness throughout the design and ensuring the stem geometry was exactly right. A well-prepared file meant these printed perfectly on the first try.
File Format Matters
STL is the standard. It's what most people use and what we prefer.
3MF is newer and better—it includes more information and handles colors/materials. Use it if your software exports it.
STEP/STP works too. We'll convert it to STL, but you lose control over the mesh resolution.
OBJ, PLY, GLTF and others are all supported, but STL or 3MF will give you the most predictable results.
Check the Scale
This sounds obvious, but I get files all the time where a phone case is the size of a house or a bracket is measured in inches when it should be millimeters.
Before exporting, double-check that your units are correct. Our system will show you the dimensions after upload—if something looks off, that's your sign.
Complex Designs Can Work
Don't let complexity scare you off. This detailed piece came out great because the file was properly prepared:
Complex detailed 3D print with intricate geometry
The secret isn't avoiding detail—it's making sure walls are thick enough and the mesh is clean. Complex geometry prints beautifully when the fundamentals are right.
The Pre-Upload Checklist
Before you hit upload:
- Walls thick enough? (1.2mm minimum)
- Mesh watertight? (No holes or gaps)
- Units correct? (mm, not inches or meters)
- Within size limits? (250mm max per side, or 340mm for H2S)
- File format good? (STL or 3MF preferred)
Need Help?
If you're not sure whether your model will print well, add "Print Assistance" when you order (it's free). I'll review the file and reach out if anything needs attention before printing.
Got a tricky design? Email me and we can figure it out together.
