MIT researchers demonstrated a tiny origami robot that folds itself into shape and then walks and swims around propelled by magnetic fields below its operating surface.
When the robot's job is done, it can drop itself into a tank of acetone and dissolve. The robot consists of a magnet and PVC layers between a laser-cut polystyrene or paper "skeleton." Heating the robot causes the PVC to contract and the body folds at specific locations, completing its self-assembly in about one minute. "Origami Robot Folds Itself Up, Does Cool Stuff, Dissolves Into Nothing" (IEEE Spectrum)