Abstract: A play structure building panel comprising of integrally connected spaced-apart curved parallel inner and outer panel walls joined by two side edges and end two end edges. One of the side edges and at one of the end edges have an integral connection means extending therefrom to mate with complementary connection receiving means on an identical panel. Accordingly, one of the side edges and one of the end edges of the panel also have the complementary connections means to receive the connection means extending from another identical panel. Therefore, any number of the panels may be connected to other identical panels along any of the side or end edges.