On a recent outing we saw a display by a local Steiner school. They were offering an activity for the children to make a twistie to wear as a bracelet or hang on their door handle.
To make, cut two lengths of wool, in different colours, about an adult armspan long. Thread a bell about one-quarter of the way along the wool. A person holds each end of the wool and twists the wool keeping the wool stretched tight. Each person twists in a different direction. When the rope is tightly twisted put the two ends together,keeping hold of the middle of the twistie to keep the wool stretched. Let go of the middle and see your twistie spring into shape.
Such a simple and neat craft idea for children.
I have found a tutorial for making twistie ropes at Mama Moontime, which gives more details (especially about how tightly to twist before letting go) and some other suggestions for using a twistie rope.