Licence terms
One-time purchase, no subscription. Every kit is delivered via Gumroad with a licence key. The calculators on this site are free and unlimited — licences only cover the model files.
The three licence tiers
Personal
- ✓ Use in personal projects and study.
- ✓ Modify for your own use.
- ✗ Commercial use
- ✗ Redistribution or resale of files
- ✗ Sharing with a team
1 machine, 1 user
Commercial single seat
- ✓ Use in commercial designs and products you manufacture.
- ✓ Modify freely for your own production.
- ✗ Resale or redistribution of the files themselves
- ✗ Uploading to public repositories
1 seat — you and your workstation
Extended
- ✓ Everything in the commercial licence.
- ✓ Team use within one company site.
- ✓ Derivative products.
- ✗ Reselling the unmodified kit as a competing asset pack
One company site, unlimited seats
Universal prohibitions: no reselling the files themselves, no uploading them to public repos or asset libraries, no using them to train generative models. Questions: support@mech-bench.com.
Third-party attributions
Open CASCADE Technology (OCCT)
The optional STEP export in this site’s browser geometry engine is built on OCCT, licensed under LGPL-2.1-only WITH OCCT-exception-1.0. OCCT is © Open Cascade SAS. Upstream source: https://github.com/Open-Cascade-SAS/OCCT (upstream version V8_0_1, recorded in the shipped manifest).
The OCCT runtime is loaded as a separate, user-replaceable file from /occt/ — it is never bundled into the site’s own code. Licence texts ship alongside the binary at /occt/LICENSE-OCCT.txt.
Replacing the geometry engine
OCCT is licensed under the LGPL, which means you may substitute your own build of it for the one we ship. The engine is not compiled into this site’s JavaScript: it is a standalone module loaded from two files at fixed paths — /occt/opencascade.js (the glue code) and /occt/opencascade.wasm (the engine itself). The filenames carry no content hash on purpose: replacement has to work without editing, rebuilding or re-deploying this site.
Artifact we ship today: 22.9 MB (22,942,327 bytes, plus 60,483 bytes of glue code). These figures are read from /occt/manifest.json, which also records the upstream OCCT version and the checksum below.
- Obtain a compatible module. Build OCCT for WebAssembly yourself, or use another trusted build, exposing the same interface as the one described in the manifest (the Emscripten factory plus the OCCT bindings the export code calls). Our own build is unpatched upstream OCCT — the manifest names the exact version and commit.
- Put the two files in place. Overwrite /occt/opencascade.js and /occt/opencascade.wasm with your build, keeping both filenames unchanged. Nothing else in this site needs to know the engine changed.
- Pick the variant that fits you. If you self-host a copy of this site, replace the two files on your server. If you use the hosted version as-is, intercept those two requests locally — a browser extension that redirects /occt/*, or a local proxy — and serve your build instead. Either way no change to our JavaScript is required.
Our build is unpatched upstream OCCT, so there is no patch set to reproduce; if that ever changes, the manifest’s patches field will list every change. For reference, the engine we ship has SHA-256 a9335919fa64bfeaee3e241d3139ad134022682429c6688e20d8ca12093d33d9.
Once you swap the files, the checksum above describes the engine we publish, not the one you are running. What follows from that depends on where you swapped them.
- Self-hosting? Update the manifest’s artifacts.*.sha256 and bytes to match your build. Two places read those values and would otherwise keep describing the old engine: this page prints the checksum, and the gear calculator reads bytes to state how large the download is.
- Intercepting the two requests instead? You cannot change our manifest, and you do not need to — read the figures above as a description of the engine we ship, not of the one your browser runs.
Refunds
Refunds are handled through Gumroad — see the dedicated refund policy page.