These are STL files, which are used commonly in 3D printing. The models were generated by OpenSCAD (programming language for 3d modeling). As I've worked more on 3D models for 3D printing, I've been wishing for visual diffs in order to make it easier to collaborate with others.

Right now, it's a pre-populated demo of a robokitty (because the internet needs more cats). But soon, you'll be able to push to your own repos using git.

Let me know if you have some feedback. Thanks!