We shared this news on the Commons village pump, but wanted to make sure we caught folks who maybe don't read the discussions there. 
In 2015 one of the most popular ideas for the Community Wishlist Survey was about supporting the uploading of 3D models on Commons.   The Multimedia team at the foundation is writing new software to make this happen with the STL file format. 
You can see how this feature works on the beta cluster for Commons.    
Note: Thumbnails might take a bit longer to generate on the beta cluster, and general performance will be a little slower than Commons. The feature is still being worked on, so things will change!
Please take a moment to join the discussion on Commons if you haven't. Questions and feedback are welcome.