By George Hart for the Museum of Mathematics


Here is a challenging star construction you can make from twelve playing cards. The underlying geometric form is the third stellation of the rhombic dodecahedron. However, there is a twist in this design that makes it somewhat tricky (but fun) to assemble.

To make your own copy, cut four slits in each of twelve cards, as indicated by solid lines in the template below. Fold each on the diagonal shown as a dotted line. Try assembling them by connecting long slits to short slits, guided by the image above. No tape or glue is needed; it all locks together when the final piece is inserted. If you give up, you can find detailed instructions here.

Catch up with all of George Hart’s Math Monday columns

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.

  • nualan


  • Goli Mohammadi

    So cool and simple! Totally gonna try this one. Thanks George!

  • Brian Givens

    Made it! This was a timely post for my star-a-day project:

  • lmm

    I not only made this one, but I made one using 30 pieces cut using the template for this one. The cards were a little heavy and I had to cheat to keep the weight of the star from pulling pieces apart as I got near the end. This is one of the few stars that I needed glue for.