Reverse geocache puzzle


[Mikal] wanted to create an awesome electronic wedding gift for his friend who was moving to France. After experimenting with a few things, he settled on creating a puzzle box that would only open in a certain location. Since his friend introduced him to the Arduino, he fittingly used one in the design, along with a serial GPS module and a mini character LCD. The box itself is locked using a servo-controlled chopstick, which could theoretically be snapped if [Mikal] really screwed something up. To save battery life, he used a small Pololu module to provide power that uses only 0.01 microamps in standby, and can be shut off by the Arduino.

The box was designed to be mysterious yet self-explanatory. When the button on the front is pushed, the box comes to life for 3 minutes, displaying the distance away from secret location. Additionally, it warns how many tries are left: the button can only be pushed 50 times before it is sealed “forever”. In order to open the box, you have to be within 2km of the destination. Theoretically, you can narrow down the location to one of 2 points after 2 readings, but a less scientific approach would probably be a lot more fun.

This seems like an amazing gift, and the same concept could be repurposed into hundreds of other devices. For extra fun, he could have placed it at a geocache location.


  1. wolfy02 says:

    thats a really awesome idea. when I read the title I was puzzled for a bit, then I had one of those duh moments. Really cool though, good to see people still geocache.

  2. markii says:

    excellent concept…
    now, Jumanji anyone? :)

  3. Andrew says:

    “As of this writing I do not think they have yet managed to open the box.”

    He will be quite happy when he finds the guy’s website :)

  4. Josh says:

    Wow. Now, that is an idea worth building on. It sounds like one of those sci-fi/treasure hunting movies where you have to be in an exact spot to activate a clue.

  5. MikeW says:

    An awesome gift, to be sure. Certainly, the contents need to be either unbearably lame, or even more awesome.

    IMHO, the best thing to put inside the box would be, like Russian nesting dolls, a smaller version of the box set for yet another location. The recipient’s head just might explode, eh? Any guesses as to what words might flow from his mouth upon opening the box.

  6. David S says:

    Awesome idea MikeW. How funny would that be?

  7. GenesisOfMoY says:

    Mikal – Brilliant! The hack, the puzzle, the gift. all brilliant.

    MikeW- One could use the same electronics for every successive box, just shedding the outer shell.

    I would like to see fewer external electronic. maybe a rotating wooden wheel of runes. or screen projected from the inside.

  8. dwabbit says:

    I have a wallet like that it will only open when wife is nearby. But I do love the idea by josh aswell

  9. McSquid says:

    That is awesome! and i love the idea of multi staging this. it would be so fun and even better as a gift. I’m thinking marriage proposal with the ring in the like 6th box =)

  10. I…love this.

  11. Reid says:

    One concern…what’s it going to look like when his friend gets on an airplane with this thing? I can’t imagine that wound end well…

  12. you could add clock and only allow it to open at a certain time AND location…

    OR you could have multiple geocache locations, so maybe there is a “3 step” combination and in order to unlock the box you must go to each location in the right order and push the button at each of them…

    the box would tell you if you were right and maybe scroll some text with a clue to the next location.

    I really love this device, it’s a very cool concept.

  13. Olivier says:

    @Reid : it’s ok, the secret location is in jail anyway.

    And for someone moving to France, the best gift is a rope. I feel very sorry for the guy, he’ll regret it very quickly :(

  14. tim says:

    it is not so comon to have only positive comments,
    very nice toy indeed

  15. Haha says:

    when you fly internationally you must clear security – this project would get your party cavity searched or tasered.

    Best gift ever…

  16. Ken says:

    Try and get this on the plane to France, “no I did not pack this box”. All those wires look great on an x-ray machine.

  17. sol says:

    Wonderful project!

  18. peter says:

    i like the combination lock idea… you could carve some sort of clues or whatever into the top that would signify where each location was, and instead of gps readout on the top, you could just have wooden dials that swing into place or something maybe when you get to each location

  19. jpristel says:

    Cool idea, but I’m confused as to why the GPS antenna is exposed?

  20. Dan Cardin says:

    if i missed my deadline of 50 tries, id smash it open with a sledgehammer.

  21. wow, hopefully he won’t spend the honeymoon trying to solve this, very brilliant invention.

  22. F7 says:

    You know, If he brought this to the airport then he might get to see what is inside through the xray machine.

  23. F7 says:

    Oh, and it would be even more interesting if there were some kind of secret transmitter inside. Like, every time you press it a cell phone dials out and logs to a secret twitter, and also something else that depends on location. For example, if you’re in France, it plays a really raunchy prank call to the foreign legion and tells them your current coordinates.

  24. blizzarddemon says:

    Lol good for the coal gifts given to christmas rascals. : D

  25. Skyler says:

    Ooohh…. that gives me ideas. Puzzle boxes. :)

  26. yuppicide says:

    Awesome. I’d buy one if they weren’t that expensive and you could program in your own stuff easily.

  27. Dan Dart says:

    @yuppicide They are cheap (hmm, ($20-$30) and easy to program for as they have their own API! Many projects have been made using Arduinos!

  28. Hmmm, I was struggling with what to get people for Christmas myself.

  29. Harry Barracuda says:

    Extrapolating further, we know someone who must have a wallet that contains technology like this, because it never f**king opens when he’s in the bar drinking beer paid for by others!

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