// What it does
Flags every painted patch whose effective width is narrower than your nozzle's extrusion line — these patches get silently dropped by the slicer at print time, so they print as the colour underneath. The overlay shows them in your chosen overlay colour so you can fix them before export.
Process discards is a bulk fix: each flagged patch gets merged into the colour with the longest shared border. Undo-able.
// When to use it
- Always before exporting, when a patch could be too narrow to survive slicing.
- After Brush work where small details might be sub-extrusion-width.
- After Region work on tightly subdivided meshes (lots of long thin auto-regions).
- Before sending a paid job to print — this catches the silent slicer-drop class of failure.
// How to use it
- Check tab → Discard risk. Set Extrusion width to your nozzle line (default 0.42 mm matches a 0.4 mm nozzle).
- Toggle Show discard risk. Red flags light up across the model.
- Cycle Overlay colour if red clashes with your palette — swatches plus a custom picker.
- Fix one by hand: switch to Grow, click a flagged patch, it widens.
- Fix all at once: click Process discards. Every flagged patch merges into its dominant neighbour.
// Tips
- Wrong extrusion width means flagging the wrong things. 0.42 mm matches a 0.4 mm nozzle; change for 0.6 mm or 0.2 mm setups.
- Process discards eats fine details if those details are narrower than your nozzle. By design — the slicer would have eaten them anyway. For finer detail, use a smaller nozzle.
- Overlay colour clashing? If invisible against your paint, you'll miss flags. Cycle until it pops.
Run this before every export
This single check prevents more failed multi-colour prints than any other step. Five seconds in the Check tab; minutes saved at the printer.