A while ago I was borrowing Doug's camera, and I asked George to come over and teach me how to paint with light. He said he saw a photo of Picasso painting with light, like the one below, when he was younger and figured out how to do it.
Basically, you set the camera on a long exposure, and start drawing shapes with some sort of light. The pink colored light is the light on the back of my Diana mini flash, the blue is George's black light flashlight, and the white is my iPhone LED light. I used the latter. When you see one or more of us (in addition to the lines created by the light, it's because George would make the flash go off, illuminating us. The rest of the time, the room was dark, so that the light we were painting with would show more vividly.
This image is double exposed; the painting that you see on the right is actually on the other side of the apartment.
In this image, he tried to get it so half of each of our faces lined up. This entailed me sitting on the couch and him making the flash go off, and then we switched seats and he made the flash go off again, so that the image double exposed.
He wasn't thrilled with how they came out, but I thought they looked pretty cool, so I decided to post.