The balanced S shapes are fun to make. There are quite a few of these and more to come. They are simply balanced on points recessed into the shape above. This gives them great movement. It also allows the pieces to come apart for ease of storage, shipping and cleaning. It does totally freak out the poor soul that spun it around too hard (or cat that played with it) when it comes crashing down! No worries, they are graceful and tough.