I had a look on Imdb earlier and spotted the Cube 2. I own the Cube, or at least did... I think I know who's still got it (borrowed for over 5 years).
Anyway, in the section People who liked this also liked... I'd understandably expect to see The Cube, but the other stand out film was The Sphere.
Have I missed a new sub-category of filming genre? Are there any other geometric shape based films out there? The Pyramid exists. Not sure about the dodecahedron