Schott Crump at his heart is a tinkerer. He came up with the prototype for fused-deposition modeling in 1989 as he was designing a "froggie" for his 2-year-old daughter. That exercise has turned into what is now a $3 billion technology built on 3D printing. With two huge mergers pulled off in 2013, one with makerBot and the other with Objet, Crump's company in now poised to go even futher in what he considers an industry still in its infancy. His vision for the future: metals. He's been tinkering.