A new 3-D-printing method will make it easier to manufacture and control the shape of soft robots, artificial muscles and wearable devices. Researchers at UC San Diego show that by controlling the printing temperature of liquid crystal elastomer, or LCE, they can control the material's degree of stiffness and ability to contract—also known as degree of actuation. What's more, they are able to change the stiffness of different areas in the same material by exposing it to heat.