A reverse geocache box is based on the geocaching principle… but reversed. The box is locked from the inside, and you can’t open it without traveling a bit. In fact, the box embeds a GPS to retrieve your loacation and pass it to a microcontroller. The MCU is comparing you location to a sequence of 5 (customizable) location on earth. To release the latch, you have to go at each location in the right order. How do you know where to go? The LCD display shows you a crucial information : distance to the next point. That’s all. And to add some difficulty to the game, the latch only release the five wooden rods, combined into a lock mechanism. You then still have to pick the lock, using old tricks!
You want to build your own? Here’s how you can do it! Believe me, it’s easy! It was my first project ever using electronic.