The authors thank the participating students and Dr. Magdalena Svensson at Linköping University, Sweden. We are also grateful to Professor Trevor Anderson, Professor Shaaron Ainsworth, and our colleagues at Linköping University for valuable input and discussions. The Swedish Research Council (grant VR 2008:5077) supported this research. A.O. acknowledges support from the U.S. National Science Foundation (grant no. 0121282) for development of the self-assembly model.