Full story: https://www.purdue.edu/newsroom/releases/2020/Q4/oddly-satisfying-metamaterials-store-energy-in-their-skin.html
When you press the dimpled circles on a fountain drink lid, they become either convex or concave. This demonstrates bistability: materials or structures that have two stable states. Prof. Andres Arrieta has demonstrated a patterned sheet of these domes that forms an energy-storing skin, strong enough to perform mechanical tasks, and even programmable to store and process data like a mechanical computer.
Programmable Structures Lab: https://engineering.purdue.edu/ProgrammableStructures
Mechanical Engineering: https://purdue.edu/ME