9 small STL models, each built to contain one specific mesh problem, with its checksum and the result a correct checker should report. Use them to test a slicer, a repair tool, or your own mesh code. All files are CC0: no attribution, no restrictions.
Prefer to see a result first? Open any file in the free STL Error Checker, which runs in your browser and uploads nothing.
A single closed, two-manifold, outward-oriented cube with no mesh errors.
Expected result: No errors; 1 shell. 12 triangles.
af0e2b9c4d617c8c16e1dc5366b19e30d0d769e7413e28277ea32c640e87e893214c41ed4e65bd8753147c46326ec96ca278fd0700f11cc95be44bc14a4d4eafManifest (JSON) · version 1.0.0 · CC0-1.0
A cube with one face removed, leaving an open boundary loop of four edges.
Expected result: 4 boundary edges. 10 triangles.
61e347991296e14a27cc623974a5f46a47981652443da71458facac38aa6eee8142803640947e68d16030805d19b0885e6a35219eb5b45a797f0d5e1c510966eManifest (JSON) · version 1.0.0 · CC0-1.0
A closed cube with an extra fin triangle sharing one edge, giving that edge three incident faces.
Expected result: 2 boundary edges, 1 non-manifold edges. 13 triangles.
db88a3bf2127fd53484f2ace5d665e6c8f63bd6781a5ec4e6f4fb90da3186119be8e0a4e88bebcf12fc0be7c844f6827f7e2fa5b864b89e4f8b1e8e477073807Manifest (JSON) · version 1.0.0 · CC0-1.0
A closed cube with one triangle duplicated at the same winding, so its three edges become non-manifold.
Expected result: 3 non-manifold edges, 1 duplicate faces (same winding). 13 triangles.
4e4be2f0b806f5ae16ebdfba271fa110a1983c84282769e0b3f4b43368fd446a8ddf4554b097305eff3d1ab3100c5a4266b863e3fd400ff62002bd6c6c7af6f8Manifest (JSON) · version 1.0.0 · CC0-1.0
A closed cube with every triangle reversed, giving a consistently wound but inward-facing shell.
Expected result: 1 inward-facing shells. 12 triangles.
d30b380f199d9317d202d633a22222e6ecf0f137ac71152876b738393c1aed7a1fe2c74b740e87e62506287b5c09897f0130a8b0bfe95f306f06db0fac4cae44Manifest (JSON) · version 1.0.0 · CC0-1.0
A closed cube plus one zero-area triangle whose three points are collinear. Degenerate faces are advisory, not print-blocking.
Expected result: 1 degenerate triangles (review items, not print-blocking). 13 triangles.
7c0126ec6a1cf0840d6c7e562ce726cb23a8f014150e80686a3b3070950d586dece90fe5f232c619b7c6b36504904d77138666840f834a83f9267c0f4583afe9Manifest (JSON) · version 1.0.0 · CC0-1.0
A large closed subdivided cube plus a tiny separate closed cube, a candidate for isolated debris.
Expected result: 1 isolated debris candidates (review items, not print-blocking). 19212 triangles.
244fae208cf6539207f838b574e492b7cab93b30c961e0949ccc550eddf690ef72bd5237a52c2d3bf635fe9c120652779fe47b0d3f1d00344b5b992690e766d9Manifest (JSON) · version 1.0.0 · CC0-1.0
Two closed cubes whose volumes overlap, so their surfaces cross without any shared vertices.
Expected result: 10 self-intersections, 8 contact risks (review items, not print-blocking). 24 triangles.
600e3a6e0037ceccbd0cd157321c320cb6dd21eb79b63c6668aa274c585780e0d296542455b5b3e62b36518a69051157208aaff3ca74e8ff5a06cea9185c3d99Manifest (JSON) · version 1.0.0 · CC0-1.0
A closed box whose top is a frame around a deliberate square opening, whose four-edge rim is reported as a boundary and never auto-filled.
Expected result: 4 boundary edges. 18 triangles.
cf031ba3a5a7c86c5cbd83bc76d93af89495f88716322c15281a421c775531b8058201f049b8c8ff43ee648097dd1c011dc15a5d33b5f6b63650397026ec1dfeManifest (JSON) · version 1.0.0 · CC0-1.0
Valid golden color round-trip reference. It is a small valid 3MF package (3.2 KB) with colors, used as the baseline for the 3MF Color Inspector. Not sure what is inside one? Read what a 3MF file is.
958183d6ca1cac1854b36bc7800b389abd0dc1f23da6712afc6c0fef08c5e57dManifest (JSON) · version 1.0.0 · CC0-1.0
For what each defect means and how to fix it, see what non-manifold geometry is, fixing a non-manifold STL, and fixing flipped normals.
Yes. Every file and manifest is released under CC0-1.0, so you can use, modify, and redistribute them, including in commercial software and tutorials, without asking.
They are primitive geometry, mostly small cubes, constructed in code by a script in this project. No third-party or downloaded model is used, which is why the license is unambiguous and the expected result is known by construction.
Compare its SHA-256 checksum with the value on this page. On a Mac, run shasum -a 256 followed by the file name in Terminal.
Each fixture is published twice: a binary STL and a byte-for-byte equivalent ASCII STL. A checker that parses both should report the same counts for both.
It lists the topology findings a correct checker reports for that file, such as the number of boundary edges or non-manifold edges. Findings that are advisory rather than print-blocking, like a degenerate triangle, are marked as review items.
No. The golden file is a closed, outward-oriented cube with no mesh errors, which is a topology result only. Wall thickness, supports, and slicer behavior are outside what a mesh check proves.