Engineers have developed a method inspired by the nacre of oyster shells, a composite material with extraordinary mechanical properties, including great strength and resilience. By changing the crystallization speed of a polymer well-mixed with nanoparticles, the team controlled how the nanoparticles self-assemble into structures at three different length scales. This multiscale ordering makes the base material almost an order of magnitude stiffer while still retaining the desired deformability and lightweight behavior of the polymeric materials.