The 3Doodler is a 3D pen developed by Peter Dilworth, Maxwell Bogue, and Daniel Cowen of WobbleWorks, Inc. The 3Doodler works by extruding heated plastic that cools almost instantly into a solid, stable structure, allowing for the free-hand creation of three-dimensional objects.
The 3Doodler Create goes one step further, though, as it can also print with ABS, the plastic that Legos are made out of. This is a lot tougher than PLA, but requires a higher temperature to melt.