Inspired by biological systems, materials scientists have long sought to harness self-assembly to build nanomaterials. The challenge: the process seemed random and notoriously difficult to predict. Now, researchers from the Institute of Science and Technology Austria (ISTA) and Brandeis University have uncovered geometric rules that act as a master control panel for self-assembling particles. The results, which could find applications ranging from protein design to synthetic nanomachines, were published in Nature Physics.