Nature is a constant source of inspiration for scientists, who have tried over the years to mimic — or even improve — natural materials for specific applications. Initial work focused on macroscopic properties, as illustrated in the 1860s by the development of celluloid, a modified cellulose derivative that mimics elephant ivory. Attention has since turned to the nanoscale, and we now know that the function and properties of many natural polymers are closely related to their structure. In the more complex biopolymers, the overall structure is mainly determined by the folding of polymeric chains (the DNA double helix, for example, or the secondary and tertiary structures of proteins). Despite the tools available to modern polymer chemists, however, it remains difficult to design synthetic macromolecules that can fold into structures with the precision of naturally occurring polymers. Writing in Nature Chemistry, Jean-François Lutz and colleagues now describe the simple approach they have adopted to control intramolecular covalent folding of linear polymeric chains with good accuracy.