The 3D API
The parametric lane is public and needs no key. Generation is reported honestly, including when it is unavailable.
Build a shape
POST /api/twodthreed/build with a shape id and its parameters answers a base64 STL. No account, and a concurrency cap rather than a queue.
Ask before you offer
GET /api/twodthreed/status reports which lanes are live on this deployment. A client that reads it never has to present a control that cannot work.