MeshMend

Use this when the user has an STL or 3MF file on their computer and asks whether it is printable, watertight or manifold, or why a slicer or printer complains about it: holes, open edges, gaps, flipped normals, inside-out faces, non-manifold edges or vertices, duplicate or zero-area triangles. Reads the file locally (it is never uploaded) and reports size in mm, triangle and shell counts, each problem with its count, and a verdict (ok / repairable / partly_repairable / needs_manual_review) based on a trial repair in memory, so it can say whether repair_mesh will actually fix the file. Read-only: nothing is written. Does not check self-intersections, wall thickness, overhangs or supports. Limits: 30 MiB and 250,000 triangles; 3MF build items and units are read from the file.

Use this when the user has a 3MF file (from a slicer such as Bambu Studio, PrusaSlicer or Cura, or a CAD export) and needs an STL, for all build items together or one item. Applies the 3MF’s build transforms and unit, and writes a binary STL in millimetres without changing the geometry; colours, materials and print settings are not carried over. Also reports whether the result is watertight. Never overwrites the 3MF. Runs locally; nothing is uploaded.

Use this when the user wants a broken STL or 3MF fixed for 3D printing (after check_mesh, or when they ask to repair, fix, make watertight or close holes). Writes a repaired binary STL (millimetres) next to the input or at output_path and never overwrites the original. It removes duplicate and zero-area faces, makes face winding consistent, turns inside-out shells outward and, with fill_holes: true, caps flat (planar) holes no wider than max_hole_span_mm. It is deliberately conservative: it never welds nearby vertices, never splits non-manifold geometry, leaves curved or larger holes open, and does not fix self-intersections, wall thickness or supports; those are reported for manual review. Runs locally; nothing is uploaded.