Pavel Mihaylov, an electronics and electrical engineering student at the University of Edinburgh, likes to take on DIY projects. His Soft Robot Out of Hot Glue Sticks is crazy cool, and the ingenious device moves because the tail section creates very little friction with the ground, and then high friction when it moves in the opposite direction. You can read the whole story here and find links to a detailed build sheet here: http://3dprint.com/65864/3d-print-soft-robot/