I've mentioned before when I was looking at measuring tools, John Bryant and Chris Sangwin and the book "how round is your circle". One of the interesting items from the book was a selection of metal objects that had constant width but were not spherical. You can see some of these on the front of the book.
Hendrik Ball of Grand Illusions has manufactured some of these mathematical curiosities and has also written a short article on solids of constant width.
Grand Illusions is also a great place to find other scientific "magic materials" such as nitinol memory wire, Thermochromic liquid crystals, optical gadgets and levitating magnets.
A day of Diagnostics – Doh!
6 minutes ago