I saw my first 3-D printer about 18 years ago--and it was far in advance of the sort of desktop devices that most folks think of in terms of the 3-D printing revolution. The machine I saw was a "selective laser sintering" printer, and devices like this can produce parts with incredible precision. The patents protecting this innovation are due to expire in 2014, and the theory is that this is going to lead to an explosion in cheap, probably Chinese-sourced, 3-D printers on an industrial scale. It could significantly change manufacturing.
The printer I saw being operated all those years ago could print out huge parts with exquisite detail. The quality of the output was enough that it could replicate every part of a car engine, and when assembled, each piece moved precisely as it would in the real-life metal machine. SLS machines are similar to the 3-D plastic-extruding printers you've probably seen before, but they can be far more precise due to dexterity of control possible with a focused laser.
Plastic extruding machines, also known as "fused deposition modeling" have become incredibly cheap in recent years as the key patents protecting the tech have expired. Printers that once cost tens of thousands of dollars can be matched in performance by units costing under $350. The theory about 3-D printing in 2014, as espoused by Duann Scott, an executive at 3-D printer firm Shapeways, is that the expiration of SLS patents will encourage a similar revolution.
[Image: By Flickr user Keith Kissel]