By George Hart for the Museum of Mathematics


This four inch diameter ball is a two-layer geodesic sphere. It has an outer layer of triangles connected with an inner layer of pentagons and hexagons, which is the structure of geodesic domes such as the Montreal Expo67 dome. The above design is unique, however, in that it is chiral, meaning it is different from its mirror image. If you have access to a 3D printing machine, you can build a copy of this structure from the .STL file available here.


Without a 3D printer, you can still build complex two-layer domes from commercial plastic components, by following the instructions here.


Gareth Branwyn

Gareth Branwyn

Gareth Branwyn is a freelance writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor to Boing Boing, Wink Books, and Wink Fun. And he has a new best-of writing collection and “lazy person’s memoir,” called Borg Like Me.