MoonPi Puzzle

Another remarkable puzzle only made possible by the very latest technology.

Bathsheba is an artist living in California. She explores the boundaries between mathematics and art. She uses the latest technology designing sculptures in 3D on the computer then getting them made either by having images laser etched inside blocks of optically clear glass, or, as here, by 3D direct-metal printing.

The First Puzzle

When I met Bathsheba and saw her mind boggling mathematical sculptures, I asked her if she could design a puzzle for me.

MoonPi was the result.

The puzzle arrived assembled but with more enthusiasm than sense it was soon in bits. 3 identical but extraordinarily shaped pieces plus 4 rubber balls and 4 steel balls.


I did eventually get it together using a rubber band and the rubber balls then replacing the rubber balls with steel ones and finally cutting off the rubber band.

Then in a fit of complete insanity I took it apart again to show that it had not been a fluke to solve the first time.

With the help of family, friends, visiting puzzle experts, assorted rubber bands, and much ingenuity, it remained in pieces for 3 months.

I decided it was just too difficult and glued the steel balls on as shown in the top picture. It is now reasonably difficult but by no means simple to solve.


Designed on the computer this was printed in 3D in an extraordinary manner. The printer puts down fine layers of either fine steel powder or an inert powder. The result is a fragile network of steel powder separated by the inert powder.

This object is then placed in a furnace and the steel particles are sintered together, which results in a fragile object made of an open network of steel with lots of fine holes.

The magic then happens: It is placed in a slightly cooler furnace in a pool of liquid bronze. The bronze quickly runs up into all the spaces by capillary attraction and the final result is a strong compound of steel and bronze. (for more information visit Bathsheba's website)