[youtube=http://www.youtube.com/watch?v=eKfx4Rjf0BU&feature=player_embedded]
[Rich] shares with us his build of a Peltier cooler based cloud chamber. This nifty little tool allows him to see the paths that radioactive particles take through alcohol vapor. The system he has come up with is fairly cheap at roughly $100. He’s using Peltier coolers from computers and a cheap ATX power supply. You can see a more detailed instructable here.
[via Make]