Cheaper, faster prosthetics. Lifelike copies that allow doctors to practice techniques before entering the operating room. Grade-school children who can see their creations become reality. Last year’s promises of the power and usage of 3-D printing have become this year’s science-fiction bought to life. Technology is changing economies, how we live our lives, how we educate our children. And 3-D printing has moved so quickly from the margins of innovation to the mainstream that it fascinates me.