STL Repair, Make Any Mesh 3D-Printable in One Click
Diagnoses non-manifold edges, holes, degenerate faces, and duplicate vertices - then auto-repairs them. Hand the clean file straight back to the Meshcast mold generator without re-uploading.
Drop your STL
Binary or ASCII, up to ~100 MB. Stays in your browser - we never see the file.
Auto-diagnose
Non-manifold edges, holes, flipped normals, degenerate triangles - all flagged in seconds.
Fix & download
Auto-repair runs locally. Compare original vs fixed side-by-side, then download or send straight to Meshcast.
Results
Adjust optimization
Fixing a mesh from an AI generator
Text-to-3D and image-to-3D tools like Meshy, Tripo and MakerWorld’s MakerLab are good at shape and bad at topology. The model looks right in their preview and then your slicer refuses it, or slices it into something hollow, inside-out or full of stray shells.
That is normal, and it is fixable. The usual damage is non-manifold edges where surfaces meet, flipped normals so the slicer cannot tell inside from outside, holes left where the generator guessed at geometry it never saw, and stray disconnected fragments floating near the model. Drop the STL, OBJ or 3MF above and all four get repaired in one pass, on your own device.
Two things repair genuinely cannot do, and it is worth being straight about them. It cannot invent detail the generator never produced, so features under about 0.2 mm (hair, whiskers, thin antennae) may smooth out or disappear. And it cannot give an AI model real dimensions: these tools have no sense of millimetres, so if your part has to measure 45 × 30 × 20 mm you still need to scale it yourself in the slicer.
Once it is watertight, the rest of Meshcast picks up where the generator stopped: split it into printable parts with alignment keys if it is bigger than your bed, or turn it into a two-part mold, a silicone mold or a candle mold so you can cast copies of it. Those generators are parametric and deterministic, real millimetres and watertight by construction, not generated.
FAQ
My Meshy / Tripo model won’t slice. Can this fix it?
Usually, yes. AI generators optimise for how a mesh looks, not for whether it is a closed solid, so their output commonly has non-manifold edges, flipped normals and small holes, which is exactly what the auto-fix repairs. What it cannot do is add detail that was never generated or give the model real-world dimensions, so scale it yourself afterwards.
Is Meshcast an AI model generator?
No, and deliberately not. Every Meshcast tool is parametric: you set real millimetre values and the geometry is computed the same way every time, watertight by construction. We fix and build on models, we do not generate them. If you brought a model from an AI tool, this page cleans it up so you can actually print or cast it.
What's a "non-manifold edge"?
An edge that three or more triangles share, or a triangle whose normal points the wrong way. Slicers can't tell inside from outside on a non-manifold mesh and either refuse to slice it or produce a mess. The auto-fix re-stitches the geometry so every edge is shared by exactly two triangles.
Will the auto-fix damage my model?
For sculpted / scanned models, no - VCGlib's repair preserves the visible surface. For models with very narrow or hair-thin features (under 0.2 mm), some detail may smooth out. Compare Original vs Fixed in the viewer before you download.
What if the auto-fix can't repair the file?
Some failure modes are too severe (e.g. dozens of overlapping shells from a CAD export). Open the file in your slicer's repair tool or Blender (3D-Print toolbox) and re-export, then drop the result here.
Does the file leave my computer?
No. Repair runs inside your browser via WebAssembly. The file is loaded into memory, fixed, and the download is generated on your device. We never see your model.
Why is the file size smaller even with no simplification?
Most STL exporters write every triangle as an independent unit with three full vertex copies. Welding duplicates alone typically cuts file size by ~50 %.