Painting My Guitar With Light

These photos are a few years old, but the technique is so much fun and I'm hoping to play around with it again soon. It's easily one of the most fascinating things I've ever done with digital imagery.

Put your camera on a tripod, focus it, then set it to a long shutter speed. Turn off the lights. Click the picture. While the shutter is open shine a small flashlight or pen light over the subject. Stop when you think it's bright enough. There is no way to instruct how to do this part, it really is experimental. 

If you try this technique tell me in the comments. I'd love to see what other people do with it.