The view from inside a mirrored tetrahedron.

What would it look like being inside a regular tetrahedron, but with all the walls made from mirrors?   Glad you asked. 

Here is a little movie of the above scene:

A video with the viewer stationary, balls at the barycentres of the tetrahedron's faces, and with the faces evolving from opaque to reflective over a long period of time.

And one where we go for a walk about the tetrahedron.

I generated these images while responding to a question on MathOverflow.