At my present job, I have been known as something of a crazy hacker. For reasons too complex to explain here I have decided to leave after ten years. This Friday is my last day. I decided to leave a small present behind for anyone trying to scavenge scraps from my old cube.
Several ideas presented themselves to me, but eventually I decided on creating a small alarm that would go off mysteriously when someone moved it. Despite the elaborate title, the design is simple, and not to hard to replicate.
The alarm I used is something I pulled off the scrap dock of the job. It was originally designed to provide an audible alarm for manufacturing machines. Mine is capable of about 80db on a 9v battery, but you could replicate this with a Radio Shack buzzer or other alarm circuit.
The basic idea is to have a box siting on my desk. When someone moves it, an alarm sounds, and won't shut off. This is because the box has a magnetic trigger inside, and when the box was moved from the desk, it was also moved away from the hard drive magnet I planted under the desk, thus triggering the alarm. It will shut off again if they put it back in the same place, but there will *intentionally* not be anything to mark it's position.