What we tested
| File | PrusaSlicer said | Actual problem | Result |
|---|---|---|---|
| 40 × 20 × 12 mm block, one small square missing | 4 open edges | One small hole | G-code identical to the closed block |
| Two 20 mm cubes merged, wall left between them | 4 open edges | Internal wall (4 non-manifold edges in FixSTL) | G-code identical to the clean 40 mm tower |
| 40 × 20 mm surface, no thickness | 16 open edges | Open sheet, height 0 | No layers were detected |
| Thingi10K 122126 by ecafruoy (CC BY-SA) | 20 open edges | 1 hole; FixSTL filled it into a verified solid | Same filament before and after repair (642.8 mm) |
| Thingi10K 526844 by LeftAngle (CC BY-SA) | 9 open edges | 2 holes; FixSTL filled them into a verified solid | G-code identical before and after repair |
What is going on
PrusaSlicer treats a mesh as manifold when it has no open edges; that is the only remaining error it lists. On Windows the tooltip adds a right-click repair with the Windows repair algorithm.
65 of the 200 public test files still had open edges after PrusaSlicer's repair; FixSTL repaired 14 of them to a verified solid.
What was actually wrong
How to fix it
- Check the file in FixSTL to see whether the open edges are holes, an internal wall or a sheet.
- Repair holes in FixSTL; give a sheet thickness in your modelling program.
- Re-import into PrusaSlicer; the warning icon should be gone.
- Scrub the layer preview through the area that was open.
Source: Vendor source code · github.com · PrusaSlicer 2.9.6 on macOS