Last month, the office supply chain, Staples, joined the world of 3D printing. Adding to the momentum? Amazon is in too. Or at least that's the story.vThe online retailer launched a new department offering 3D printers ($1,099 and up), 3D printing filament, parts and accessories (for those building their own machine), 3D printing books, and software, like CAD, to make 3D models.