there's this painting by Antonio Lopez Garcia that has a piece of red meat in it and rather than paint it he attached the photo he was painting from to the canvas. I forget what else was going on in the painting but that part stuck with me. I wish I could find a pic of that painting online but I haven't had any luck.
I kind of thought about that when I was working on the hand. There's a documentary on him called Dream of Light or something close to that.