The GPS puzzle box was built by Mikal Hart as a wedding gift for a friend, unlike normal puzzles this one uses GPS and the box can only be opened in a specific location.
With all the electronics, there wasn’t much room inside the box for anything too substantial. I put in a few local (US) gift cards to entice them to visit soon, a set of Kazuo Ishiguro audio books (on a USB key), and an overly sentimental card. And of course, as I pointed out in the card, if either of them fancies doing a little Arduino development, there’s a perfectly good Duemilanove to play with, not to mention an LCD, a servo, and a GPS.
The box features an LCD on the lid, press a button on the case and it will show you how far you are in KM from the loctation on the LCD screen.
You don’t get any specific directions on which way to go, so I suspect this puzzle could take a serious amount of time to solve.