The international puzzle party is an annual invitation-only 3-day event for collectors, makers and inventors of 3-dimensional physical puzzles, mostly of wood or metal. Part of the event is an 80-way exchange in which each participant brings 80 copies of an original puzzle to give to everyone else in the exchange. You go home with 80 different puzzles, many of which are one-of-a-kind. To get all the puzzles home required two and a half suitcases.

I have been going to the party ever since it started, but this was my first puzzle exchange. My exchange puzzle was a version of Convex Concave, a puzzle that started as part of my computer game Heaven & Earth and later became a paper punch-out puzzle in Games magazine.

For this incarnation, puzzle prototyper George Miller suggested I print the pieces on magnetic material. I was fortunate to link up with Amina Allen, who manufactures geometric magnetic puzzles, to do the manufacturing. I got existing black square magnetic boards from Fractiles, who sells a wonderful magnetic tiling toy called Fractiles, shown below, that makes unique art and designs with seven-fold geometry.

Here are the instructions and answers. The puzzle itself can be purchased directly from me for $30; email me if you are interested.