The most complex crystal designed and built from nanoparticles has been reported by researchers. The work demonstrates that some of nature’s most complicated structures can be deliberately assembled if researchers can control the shapes of the particles and the way they connect using DNA. Potential applications of the cage-like structures, called clathrates, include controlling light, capturing pollutants and delivering therapeutics. New types of lenses, lasers and even Star Trek-like cloaking materials are possible.