Additive manufacturing, also called 3D printing, is the process of making solid objects from a digital model. 3D printing uses additive processes, where an object is created by laying down successive layers of material. Traditional machining uses subtractive processes, in which material is removed from a solid block by milling and cutting.
MakerBot boldly opened a retail store in NoHo, Manhattan, where one can buy Replicator printers, and launched Thingiverse, a site where you can download 3D objects to print. Additional retail stores have since been opened in Boston, MA, and Greenwich, CT.
In his book Makers, Chris Anderson posits that 3D printing is creating a "desktop manufacturing revolution," ushering in a new age of entrepreneurship. It's an optimistic look at a possible rebirth of American manufacturing.