Ez3D3D printing replacement parts: the practical workflow
The single best use of a home 3D printer is replacing the $4 plastic part that broke and discontinued the whole appliance. Here's how to actually do it, without CAD.
Replacement parts come in three flavors, and each has a fast path in Ez3D (a free, browser-based part designer: no account, works offline, files never leave your machine):
Flat parts: trace them from a photo
Gaskets, cover plates, mounting brackets, spacers, blanking plates, or anything flat with constant thickness. Lay the broken part on white paper, photograph it from above, and Ez3D traces the outline and holes into true geometry. Set the real size with two clicks on a ruler in the photo, type the thickness, export the STL. The full photo-to-STL guide walks through it step by step.
Even a shattered part usually works: arrange the pieces on the paper, trace, then drag the outline points to bridge the cracks.
Round and standard parts: rebuild from a template
Knobs, washers, standoffs, hooks, feet, plugs, cable clamps. These are parametric shapes, and measuring beats tracing. Grab calipers (a $10 pair is fine), measure the old part's key dimensions, and type them into the matching ready-made template. A drawer knob is genuinely a 60-second job.
Parts that screw in: get the threads right
Printable screw threads are where most "easy" design tools tap out. Ez3D's fastener library (Pro) generates real, working threads: nuts and bolts, threaded rods and sockets, and tapped holes, with an adjustable fit gap so the printed thread actually turns. For metric hardware, that means a knob that threads onto an M8 bolt, printed at home.
Getting dimensions right the first time
- Measure twice, in millimeters. Everything in Ez3D is exact mm (you can type inches too: "0.75in" converts automatically, and readouts show both).
- Holes: add clearance. A bolt needs a hole slightly bigger than itself: 5.3 mm for an M5 is a good start. FDM printers also shrink holes slightly.
- Check the gap. Select two parts and Ez3D shows the exact gap between them, which is handy when a lid needs 0.2 mm of clearance to fit.
- Use the print check. It flags parts too big for your printer's bed (it knows your model: Bambu, Prusa, and Ender presets are built in), paper-thin walls, and floating geometry before you waste filament.
What about parts someone already modeled?
Always check Printables, Thingiverse, and MakerWorld first. If your exact part exists, download it. The workflow above is for the long tail: the discontinued bracket nobody else has modeled. (With Ez3D Pro you can also import an STL you found and modify it: resize it, cut it, or build onto it.)