This metallic wire shaped in a form of a spring is made of a special alloy of nickel and titanium (commonly termed a shape memory alloy) that is able to contract 4% or more when heated and then return to its original shape when cooling. This material’s ability to contract upon heating makes it useful in mechanical devices where heat, which is usually precisely delivered through an electric current, is used to generate some kind of motion. Shape memory actuators (SMA) are found in a wide variety of applications, from medical devices (portable insulin pumps) to computers and vending machines. Explore shape memory actuators on the Institute of Making website: https://www.instituteofmaking.org.uk/materials-library/material/shape-memory-actuator.