Here is a video with the Duocylinder, wormhole, and a few other manifolds. The womhole between parallel planes is actually what I did in the previous video. Also, I think the closest I can get to the Klein bottle right now however is the Mobius strip in the previous video since the Klein bottle has a 2D surface despite requiring 4 dimensions to embed. To show it off with a 3D surface I think you would need 5?
Once I work on the menus and settings I'll allow the player to toggle gravity and free cam.
It'll likely be a while before I can get to different kinds of manifold descriptions (alternatives to proj fn), but it is something I'll try eventually. Rendering general geodesic equations would definitely be interesting.