How to fix non-manifold edges

Bambu Studio, PrusaSlicer, or Cura flagged "non-manifold edges" on your model. In plain terms: an edge in your mesh is shared by more than two triangles — geometry that can't exist as a real solid object. Printers need watertight, physically-possible shapes, so slicers either refuse the file or produce broken walls and gaps.

Why it happens

Non-manifold edges usually come from boolean operations (merging or subtracting shapes) in CAD, meshes exported at low quality, sculpting tools pinching geometry together, or files that were converted between formats one time too many.

How to fix it (about 30 seconds)

1. Open the Ferdelance checker and drop in your .3mf or .stl — no account needed to inspect.
2. The 3D view highlights every non-manifold edge in red so you can see exactly where the problem is.
3. Click Auto-Repair: the pipeline splits the bad edges, rebuilds the surrounding surface, and re-checks every part until the mesh is watertight.

More fix guides

• Your 3MF isn’t watertight — here’s the fix
• Fix holes and missing faces in your model
• Repair a 3MF without losing your AMS colors
• Free STL repair that never uploads your file