An unexpected sister piece to Butterfly Bot from I, Robot. An enthusiast e-mailed me that he had tattooed the Butterfly Bot insectoid on his arm, and would I consider doing a robot caterpillar, so that he might ink the other arm? I thought it was a grand idea, and a couple years later, I got around to it. Unfortunately, my enthusiast was by then past the tattooing phase of life, and contented himself with a print.