Math Monday: Make a Ball of Cards

Craft & Design Science
Math Monday: Make a Ball of Cards

By George Hart for the Museum of Mathematics

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Two years ago, we looked at some constructions made from playing cards that are slotted and slid together. Here is a new one, by Zach Abel.

Thirty cards are required, and each is slotted as in the template below. To build your own, simply copy this pattern onto thirty cards, cut on the red lines, and assemble as in the image. Note that Zach’s version above has some cards facing in and some facing out, however, the template must always face the same way. So if you want some cards to face differently, turn them over before coping the template on them.

Notice how sets of five cards meet at their short edges form six different prism-like “equators.” The construction approximates the uniform compound of six pentagonal prisms, but with rectangular sides instead of squares.

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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. His free weekly-ish maker tips newsletter can be found at garstipsandtools.com.

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