The K-dron: a shape with eleven faces that nobody had noticed before 1985

The K-dron is a solid with a square base, a rhombus on top and nine more faces around them, eleven in all. Two of them, tops together, make a cube. Janusz Kapusta found it in January 1985 while preparing an exhibition in New York, called it the K-dron, and patented it. Even the name is eleven: dron from the Greek for a face, and K because it is the eleventh letter of the Latin alphabet.

He has come up with uses for it in furniture, toys, clocks, bottles and floors, and a hollow building brick made from it is in production. It is also sold as a puzzle for children, Łamacz głów (“Brain-teaser”): eight K-drons in two colours, which the maker says can be laid out in 38,416 ways. The town of Koło, near the village where he was born, has a K-dron monument. It is also, as he tells it, the shape that made eleven start following him. That story is here.