I'll split these below 4 things into separate subtasks:
- Create Template:3dpatent, which will be added to 3D uploads
- Make Special:UploadWizard add {{3dpatent}} to 3D files that have been uploaded (if patent agreement has been accepted, which is required to be able to upload)
- Make Special:Upload add {{3dpatent}} to 3D files that have been uploaded (will need to alter custom JS)
- Create tracking category Category:Files_with_no_machine-readable_patent for 3D uploads lacking {{3dpatent}}