How to Design a Bracket for 3D Printing (Step by Step)
A mounting bracket is the perfect first 3D-printed part: simple geometry, genuinely useful, and a great way to learn the rules that make a print strong. Here is how to design one from scratch — no CAD experience required.
What makes a bracket print well
Before drawing anything, four things decide whether your bracket survives the printer and the job it is for:
Wall thickness
Aim for at least 2–3 mm (about 0.1") on load-bearing walls. Thin walls print fast but snap.
Hole sizing
FDM printers shrink holes slightly. Add ~0.2–0.4 mm to the diameter, or plan to drill/tap after printing.
Fillets at corners
Round inside corners. Sharp internal corners concentrate stress and crack first.
Print orientation
Layer lines are the weak axis. Orient the bracket so load runs across layers, not along them.
Step 1 — Describe the bracket
With PartWork.ai, you do not have to extrude and constrain by hand. Open studio.partwork.ai and describe the bracket in plain English:
Create an L-shaped mounting bracket, 60 mm tall and 60 mm deep,
4 mm wall thickness, with a 6 mm fillet on the inside cornerThe AI generates editable 3D geometry from that sentence. You can rotate it, measure it, and keep refining — see Creating Parts for more on writing effective prompts.
Step 2 — Add the mounting holes
Select a face and add holes by describing them:
Add two 5.2 mm holes on the vertical face, 20 mm apart, centeredThe 5.2 mm (instead of 5 mm) leaves room for FDM shrinkage on an M5 bolt. Need to tweak a dimension after seeing it? Just say so — "move the holes 5 mm higher" — and the part updates. More on this in Modifying Parts.
Tip
Add a small chamfer to the top of each hole. It helps the print finish cleanly and makes bolts self-align.
Step 3 — Export an STL and print
For 3D printing you want an STL (or 3MF) file. Export it, drop it into your slicer, and print. If you later want to CNC the same bracket in aluminum, export a STEP file instead — we cover the difference in STL vs STEP. Full export steps are in Exporting.
Design your bracket now
Start with 2 free AI generations — no card required
PartWork.ai runs entirely in your browser. Describe a part, get editable 3D geometry, export for printing or machining. Open the studio and design your first bracket. Need more after your free generations? 100 credits are $4.99 (about 5¢ each).