By George Hart for the Museum of Mathematics

In 1995, I designed this hypothetical construction and posted a computer rendering of it online. It is called “Nailbanger’s Nightmare” because I thought it was far more complex than any carpenter would ever want to make.

After fifteen years, I was surprised to receive an email from Thomas Guethner of Trostberg, Germany, showing me that he has constructed a physical version of the structure. There are 480 wooden struts (60 in each of 8 slightly different lengths) all held together with 960 screws. The result is half a meter in diameter.

Thomas tells me “I want to thank you very much for this fantastic idea to get rid of some scrap wood.”

Then I was surprised again when just a few weeks later I received images of another approach to making Nailbanger’s Nightmare, this time from Canada. David Gunderson, at the University of Manitoba Mathematics Department, is developing an approach in which the struts have slots cut into their ends. The image shows how the sticks assemble with a friction fit.

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