3D printing is an up and coming technology that has revolutionized prototyping and is poised to do the same for manufacturing. The Economist wrote a 2011 review on this technology at www.economist.com/node/18114221. Already an estimated 20% of 3D printing is used to generate final products as more and more materials have been adapted including styrene, nylon, glass, ceramic, steel, titanium, aluminium, and silver.
The common Computer Numerical Control (CNC) devices are subtractive in that they remove material from a block of starting material using drills, water jet cutters, or laser cutters. 3D printers on the other hand are additive, building up the material one layer at a time in a manner not unlike a common ink jet printer. The new layer of material is added to the underlying layer either by targeted heat fusing each layer together or by laying down a layer of binder (glue) between layers of material. This results in less waste.
The advantages of 3D printing include: the capability of reliably producing highly complex parts, low labour requirements (aside from the knowledge-intensive design), efficient low waste additive processes, an ever increasing range of materials, and fast local production. All of these factors should make it cost competitive with the current processes and disruptive to current manufacturing methods.