# Math Monday: Quilted Geometric Spheres

By George Hart for the Museum of Mathematics

Anabeth Dollind made this assortment of quilted balls, based on tilings of the sphere. These first two are spherical versions of Platonic solids: the dodecahedron and icosahedron, with twelve pentagons and twenty triangles, respectively.

Next are a spherical version of the icosidodecahedron, which has twelve pentagons and twenty triangles combined, and its dual, the rhombic triacontahedron, which consists of thirty rhombi.

And here are a couple that incorporate squares, the rhombicuboctahedron and the truncated octahedron.

There’s no limit to the possible geometric designs and fabric combinations. You just need a needle, thread, scissors, fabric, and stuffing. Choose a design, cut out polygons with a common edge length, and hand-stitch the edges. See what you come up with!

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See all of George Hart’s Math Monday columns

## 4 thoughts on “Math Monday: Quilted Geometric Spheres”

1. Keith Trnka says:

These kinds of patterns are commercially used for footbag/hackysack (see http://worldfootbag.com/ for instance). If you’re interested in that, I suggest changing normal stuffing for popcorn kernels, which makes for some nice homemade footbags.

2. ローレックス says:

アンティーク ロレックス ローレックス http://www.pia5.comrolexロレックス-m0owb-2.html/

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### 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 man’s memoir,” called Borg Like Me.

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