Origami can now fold itself—at least when it’s made with a certain kind of plastic. Polystyrene, used in plastic cups and Styrofoam take-out containers, shrinks when heated. That made it an ideal material for researchers who used color printing and light to get thin 2D sheets to fold, step-by-step, into complex 3D shapes. Engineers covered the sheets with lines of ink, matching different colors with the colored light they absorb. As the light strikes the lines, the plastic underneath heats up and shrinks along the printed line, creating a “hinge” that folds the sheet. By shining varied sequences of light onto printed patterns, scientists were able to control which parts of the sheet folded first. And with a diversity of printed designs, inspired by the art of origami, they used light to fold boxlike shapes, pyramids, and even helices, they report today in Science Advances. The engineers suggest the new technology might someday be useful in smart packaging, deploying satellites, and implanting medical devices less invasively. One application already in use? Education. The team has taken its light-activated origami to schools and science fairs, hoping to get kids excited about materials science and engineering.