"Tensegrity" is a term that refers to a structural system of floating rods in compression and cables in continuous tension. It combines the words "tensional integrity," and has been used as the structural basis for several architectural projects such as the roofs of the Georgia Dome stadium and the Olympic Gymnastics Arena in Seoul, South Korea, as well as a large pedestrian bridge in Brisbane, Australia. It's also the system that was used by a research team from the Georgia Institute of Technology to create 3D printed objects that significantly expand when placed in water. Learn more about these structures at 3DPrint.com: http://3dprint.com/178185/3d-printed-shape-changing-objects/