Zometool is widely used for mathematical constructions, and can also be used for constructions of complicated 3D models [3]. For complicated constructions, this is not an easy task and the user can easily become confused. We developed an AR (augmented reality) system for constructing complicated 3D Zome models. With this system, the target Zome model appears on a smartphone screen overlapped to the image of the physical Zome model under construction, and one can easily see how to connect the struts to complete the model.