It’s like origami, but hands-free. Magnetic microparticles can be mixed into rubber to make 3D printed shapes that fold, morph, and move in the presence of a magnetic field.

Xuanhe Zhao at the Massachusetts Institute of Technology and his colleagues made these shapes using silicone rubber infused with magnetic microparticles .

They modified the nozzle of a 3D printer by surrounding it with coils of wire that act as an electromagnet. When the rubber is extruded, the microparticles become magnetically aligned along the direction of the magnetic field from the wire. The team could also change …