Calder Mobile Always start building a mobile from the bottom! Then build up level by level, balancing each hanger. Be sure that the mobile can move - parts should not collide! Various materials can be used As hangers you can use e.g. branches, straws, chopsticks - and of course metal thread. The law of gravity Many laws can be bend or circumvented - the law of gravity cannot!!! The suspension point is always to be above the point of gravity.