Engineers from MIT have created 3d printed structures that can be controlled with magnets. They have created a new kind of 3D printing material that ends up soft to the touch but embedded with magnetic particles.
The desired shape is then printed with a magnet next to the printing nozzle. This magnet orients the magnetic particles in the same direction when the object is being printed.
The tiny robots may one day be used inside your body to do things like control a blood vessel or deliver drugs to a specific location.