Basically, as the name implies, Mikal Hart's box is dependent upon the GPS system. In this case as long as you figure out (by reading the GPS-enabled diplay screen on the top of the puzzle box) within 50 guesses the pre-programmed "mystery location" the box will spring open revealing its contents.
There are several cool aspects to this: One is that you have to play a location game tied to satellites to make your present work, another is that in a perfect blending of high-tech and low-tech the device that interfaces with the electronic latch to make it work is a modified chopstick!
It really is worth reading the whole "Reverse Geocache Puzzle" saga yourself at Mikal Hart's website and checking out the goodies and gizmos at the Arduino website as well!
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