3-D printing technology, used industrially for the last few decades, is poised to break into the mass market. Its endless and swiftly developing possibilities—from entrepreneurial manufacturing to the potential sculpting of human organs—could become the next industrial revolution. … Assembling, screwing together, adhering, welding—all these processes are rendered obsolete when even the most complex shapes can be produced by a single machine using this casting technique. The end result can be an artificial hip, a hearing aid, a cell phone case, customized footwear or even the Urbee, a prototype car that has been making a splash. … The only limits...