The 3Doodler is the first 3D printing pen which lets you design complex creations or just doodles. The $97 pen works by taking a single colored piece of plastic and feeding it through the pen at the top. Then you touch a piece of paper or circle the air, and the now-melted plastic comes out at the tip solidifying to create a 3D model. And you thought your mindless doodling was worthless.