Boy’s surface week we build some self-intersecting Boy surfaces: pick your favourite(s).

Polyhedral versions: page 48 (the Topologicon is available in many languages besides English)


Sliced solids greatest thing since sliced bread.

Enjoy! We’re starting with this post a brand new column “Handy Math” – it’s dedicated to Professor Feynman of course.

PS Yes dear readers, watch for another new column later in the week.