Wax-coated plastic morphs between soft and stiff
Heat-controlled materials could serve as skeleton for shape-shifting robots

WAX ON, WAX OFF Coating a plastic scaffold in wax (left) makes the squishy structure stand firm. Without wax (right), or when the wax is heated, the scaffold is easily crushed. Robotic body parts made of the wax-plastic duo could let machines toggle between hard and soft.
Courtesy of N. Cheng et al