model/stl

An STL mesh, as 3D printers take.

Extensions
.stl
Header
Content-Type: model/stl
Registered
Yes, in the IANA media type registry.
References
IANA

What servers send

The type each server's own mime.types gives these extensions, as it ships.

ExtensionApache httpd 2.4.69nginx 1.31.6
.stl application/vnd.ms-pki.stl Not listed

Common model types

Every media type, in one table