Shuhei Furukawa from Kyoto University’s Institute for Integrated Cell-Material Sciences (iCeMS) and colleagues in Japan synthesised polyhedral-shaped porous molecules that rotate in a double layer of lipids, exposing different-shaped openings. These openings allowed the molecule to conduct ions from one side of the artificial lipid membrane to the other in two distinct ways. Chemists had previously synthesised molecules that conduct ions across a lipid membrane, but incorporating two different openings into a single molecule remained elusive.