Snappy - Quick Start
Snappy — Quick Start
Make parts that actually fit together, first print. Snappy cuts a shape out of another shape and adds a real, printable clearance so the two pieces slide, press or snap together the way you intended.
Install and open Snappy
Download the Snappy ZIP (Free or Pro) and leave it zipped. In Blender, open Edit → Preferences → Get Extensions, click the ▾ menu at the top-right and choose Install from Disk…, then pick the ZIP. Snappy installs and switches on by itself — you can confirm it is ticked under Add-ons.
To open it, move your mouse over the 3D viewport and press N to show the sidebar, then click the Snappy tab down the right-hand edge. Everything lives in that sidebar. If the tab is not there, press N again with the mouse over the viewport — the sidebar is hidden by default.
Before anything else: prepare the scene
Snappy works in real millimetres. If the scene is not in millimetres, a "0.2 mm" clearance will not be 0.2 mm on the printer. Open the Snappy tab in the 3D viewport sidebar (press N) and click Prepare Scene Units.
Your first cut FreePro
- Model two things: the part you want to cut into (the base), and the shape you want to fit into it (the cutter). Position the cutter where the hole should be.
- Open Material Fit and pick your filament and nozzle size, then choose a fit: Tight, Normal or Loose.
- Select the base, then shift-select the cutter so the cutter is active.
- Open Cutting Sets and click Make Cut.
Snappy builds a clearance-expanded copy of your cutter, subtracts it from the base, and leaves the cut live so you can keep adjusting it.
Choosing a clearance
Start with Normal. Print, test the fit, then adjust. Reasonable starting points:
| What you are making | Try |
|---|---|
| Press fit — needs a tap to seat, stays put | Tight (~0.10 mm) |
| General fit — slides together by hand | Normal (~0.20 mm) |
| Free-moving — lids, sliding parts | Loose (~0.30 mm) |
| Hardware pockets — nuts, magnets, bearings | Custom, usually 0.10–0.20 mm Pro |
Not sure? Use Export Clearance Test in Scene Setup. It generates a small printable coupon with a range of clearances so you can measure what your printer actually does.
Use the exact same print settings for the test as you will use for the real part — filament, nozzle, layer height, temperature and speed. Clearance changes with all of these, so a coupon printed with different settings gives you a number that will not carry over to your part.
Important: clearance stays adjustable for as long as the cut is live. Print, test, change the preset, print again. Do not apply the cut until you are happy with the fit — applying is permanent.
Cutting sets Pro
A cutting set is every cutter attached to one base object, kept together in one place. You can show, hide or reset them all at once, or tune any single cutter without touching the rest.
And a cutter does not have to be a part you are printing. It can just be a hole — a nut trap, a magnet pocket, a bearing seat — with the same clearance control, so the real part actually drops in.
Two controls are worth knowing early.
Export decides whether a cutter's printable part comes out when you export. Turn it off for cutters that only make a hole, and Snappy still cuts the hole, but will not hand you a part you were never going to print.
Operation and solver are set per cutter, not globally. One cutter can subtract while another intersects, and if a single cut misbehaves you can change just its solver without disturbing the rest.
A different clearance for every cutter
Open Selected Cutter Options and tick Custom clearance for this cutter. That cutter now keeps its own value — so a press-fit peg at 0.10 mm can sit alongside a nut trap at 0.15 mm on the same model. Cutters without it keep following the fit preset, and changing that preset leaves your custom ones alone.
Protect Faces
Sometimes a face must stay exactly flush — a mating surface that should not be pushed out by the clearance. Enter Edit Mode on the cutter, select those faces, and click Protect in Selected Cutter Options. They are excluded from the clearance expansion.
Working with dense models Pro
Booleans on a high-poly base get slow. Turn on Low Resolution Preview in Troubleshooting and Snappy swaps in a lightweight stand-in while you position the cut. The exported geometry still uses the full-resolution mesh.
Exporting
You do not need to apply a cut before exporting — Snappy bakes the geometry into the exported file for you.
- Export Current Set — the base and parts for the cutting set you are on
- Export All — everything in the project
- Send to Slicer Pro — writes the files and opens them in your slicer in one click
Exported parts are named with the clearance they were cut at, so Round_Peg_PRINT_ME_0.2mm.stl tells you exactly what you are holding when three test prints are sitting on the desk.
Applying a cut — the last step
Applying is permanent. It bakes the cut into the base and deletes that cutter, its outline and its printable part. Export anything you still need first.
Most of the time you never need to apply. Keep cuts live so clearances stay adjustable, and use the Export toggle to leave hole-only cutters out of your exports. Apply when you are finished and want a clean, baked mesh.
If something goes wrong
| Symptom | Try |
|---|---|
| Cut looks wrong or leaves shards | Troubleshooting → Try Next Solver |
| Cutter mesh has problems | Troubleshooting → Diagnose Geometry |
| Clearance seems wrong on the print | Check Scene Setup says "Units ready: millimetres" |
| Viewport is sluggish | Turn on Low Resolution Preview Pro |
| Want to start over | Reset Cut Set, or Reset All Cuts in Project |
Free vs Pro at a glance
Free gives you the complete fitting workflow: clearance-aware cuts, the fit presets, the printable calibration test, geometry diagnosis and export — one cutter per base.
Pro adds multiple ordered cutters per base, a different clearance for every cutter, per-cutter solver, colour and visibility, Union and Intersect, protected flush faces, the high-poly preview, and one-click slicer handoff.