Algodoo

these linkages can be used in unison with each other to make chains, chains with rotating circles, worms, bridges, whatever you can imagine! I grouped them, and all you have to do is copy them and, using the grid, drag them onto another linkage ["=" needs to be dragged to "0", not "0" to "="] and it will work. Play around with them and tell me how i can make them better, or what else I can add to them!