We have designed a hub and strut kit that interfaces to a 3D graphics application. FlexM is a prototype flexible physical interface for manipulating and building 3D geometry. Using the FlexM hub and strut components, designers can build and explore 3D geometry with the ease of a toy and the power of a computer. The hubs transmit the model's topology and geometry to the computer, where the model is rendered on the screen in real time. The paper reports on the iterative development of several versions of the project.