Last spring I backed the 3Doodler project on Kickstarter. Advertised as “The World’s First 3D Printing Pen,” the device works a lot like a hot glue glue. You insert strands of colored plastic (ABS or PLA) into one end and the other end heats the plastic such that it flows out the tip, allowing you to literally draw in the air. I’ve experimented with freestyle 3D sketching, as well as tracing shapes from templates and “welding” the edges together. It is one of my new favorite toys.