Elastic polymers, or ‘elastomers,’ have various applications, including in car tires and shock absorbers, and their properties are governed by the density of cross-linked polymer chains. However, these properties are usually not modifiable, leading to excessive synthesis requirements. Now, scientists have come up with a novel elastomer film whose elasticity can be ‘tuned’ in a post-preparation manner, enabling unique elongation and fracture properties, and opening doors to flexible displays and soft robotics.