As teased, here are the videos of the hydro-cordial muscles in action. These muscles are created by adding an additional step to manufacturing where before annealing you wrap the twisted nylon around a bolt under tension. Then after annealing it holds the structure of a spring. This was originally discovered by research students at UCLA I believe and the creation of which had eluded me until recently. The point is that it trades some strength for a great deal of contraction. As described if you wrap the material around the bolt in the same direction as the twisted nylon the muscle will contract under heat. If you wrap it the opposite it then the muscle will expand under heat.