3D viewer for Craft CMS
I know a lot of 3D programs are going to use different file formats. And the viewers tend to vary quite a bit. What are you using?  If you can export to obj format, three.js seems popular. 

There's also services that do the heavy lifting of embedding as well. (Kind of like Vimeo for models). Just did a little bit of searching, SketchFab seems interesting and they also offer a free plan. They accept a bunch of file formats plus an API which you could tap in Craft. 

They also do oEmbeds so you could use something like Embed Assets to hook into it.