A 3D pen is a pen that extrudes heated or warm plastic from the pen’s nozzle. You don’t need any software. With a 3D pen you can draw a raised graphic on a piece of paper or any flat surface. But what makes a 3D pen truly unique is its ability to “draw” in mid-air, allowing you to instantly form 3D structures right in front of you, which you can pick up and hold in your hand.