I want to do more time-lapse photography without having to trigger the camera manually. I also didn't want to spent over $100 for a professional model, so I built this one for about $20 (not including the empty Altoids tin). It's a snug fit between the electronics, switches, 9V battery and wires, so the rubber bands keep it securely shut.
The switch on the bottom is on/off, other switch is for long or short periods between pictures. The potentiometer varies the time from 3 to 30 seconds (short setting) and 30 seconds to 4:30 minutes (long setting). At the other end is a 3.5mm phone jack that I plug the camera into.
Hopefully I'll get out and use it tomorrow.
Strobist info: Canon 430EXII into umbrella to left of camera. Tin is resting on 'custom Lego stand' on top of white foam core. Exposure bumped up in Lightroom.
Update: First test shot of a sunset posted on Vimeo. Be sure to watch the HD version.