# Polymend

> Polymend (https://polymend.xyz) is a free, open-source online mesh repair tool for 3D printing. It repairs the small mesh faults that slicers flag in STL and GLB files. It runs entirely in the browser; files are never uploaded.

## What it does

- Fixes the mesh faults slicers report as open edges, non-manifold edges and reversed faces: it removes stray triangles stuck to the surface, patches small holes (up to 100 edges), and turns wrongly facing triangles.
- Repairs up to 20 files at once (up to 1 GB in all), lists how each went, and downloads every repaired model in one ZIP with a summary.
- Converts GLB to STL or 3MF, turning the model upright and letting the user set a print height in millimeters.
- Shows the model before and after, side by side, with every change marked, and reports "Repaired", "Nothing to fix" or "Partly repaired".
- Leaves original vertices where they are, except that points a hair apart along a seam are joined. A model with no faults is not changed at all.
- It is deliberately narrow. It does not fix large holes, wide openings, thin sheets with no thickness, self-intersections or badly damaged scans; it leaves them alone and reports "Partly repaired".

## Facts

- Input: GLB (binary glTF, including Draco-compressed) and STL (binary or text), up to 200 MB or 1 million triangles. Up to 20 files at once, 1 GB in all. Meshopt-compressed GLB is not supported.
- Output: binary STL, 3MF in millimeters, or a ZIP of both. Color and texture are not kept.
- Privacy: no upload, no analytics, no cookies; the page's Content-Security-Policy forbids network connections.
- Speed: a 300,000-triangle model is repaired in about a second; a 1-million-triangle model in a few seconds.
- Evidence: twelve detailed figure models, each with 6 to 54 non-manifold edges and 16 to 114 open edges, were all repaired to zero and then passed the mesh checks of Bambu Studio and a second slicer. Fifteen CAD-exported parts were left untouched or lost only collapsed or stray triangles. Of eight museum 3D scans, two were already sound, two were repaired, and four with heavy damage were reported as "Partly repaired".
- A rigged or animated GLB is read in its rest pose; any moment of any of its animation clips can be chosen and repaired instead.
- Cost and license: free; MIT license; source at https://github.com/heyhaigh/polymend
- Made by Ryan Haigh (https://heyhaigh.ai).