Researchers developing a 3D-printing process in Sheffield, UK, claim that it will be able to make parts as cheaply and rapidly as injection molding. A Colombian designer used a 3D printer to model pediatric artificial limbs that use fanciful Lego designs, such as a laser-blasting spaceship. And a 3-year-old Chinese girl whose head was three times the normal size now lives a normal life thanks to a 3D-printed skull implant.