A pen that uses plastic for ink allows you to draw in three dimensions. The 3Doodler, invented by Peter Dilworth and Maxwell Bogue, gives people a freer hand in creating sculptures and brings computer-aided design software front and center.
You hold it just like a regular pen, but instead of building a shape layer by layer, as a 3-D printer does, this pen it extrudes the plastic into the air.
The plastic is soft when it is extruded, but it hardens quickly enough that it can form a stable structure. It’s the same kind of plastic (called ABS) that is used in 3-D printers. The pen is hooked up to the supply of plastic, which comes in the form of long, thin strings, so it has a kind of tether on it. It doesn’t need a computer or any software to work.
The demonstration video shows some of the thing it can do: lifting the pen from a surface, for instance, leaves a straight line of plastic standing up. “Scribbling†would make layers of plastic for a stronger support if it’s vertical.
While it seems remarkably easy to use, there might be some hurdles if you get one. Drawing would require a steady hand, and it would be slower than using a pen (the video on the Kickstarter site is sped up in places, so it doesn’t always show that controlling the “line†might be a painstaking process). You’d also have to be aware that what you draw has to stand up under its own weight.
source : http://news.discovery.com/tech/gear-and-gadgets/get-a-pen-to-draw-in-3d-for-75.htm