scanner: hall effect ring

I quickly made a ring that Nathaniel can use to trigger the hall effect sensors on the scanner. He can wear this on his hand and then wave it in front of the scanner case to turn the scanner on, and then take a 300 dpi scan. The ring has a small magnet that sits in the top. I used a small steel cap head bolt to connect the top "setting" housing to the base ring, so the magnet wants to stay in the "setting" because it's attracted to the steel bolt. The bolt is threaded into a small hole in the ring.