Polymer clay is a modelling material that cures when heated from 129 to 135 °C (265 to 275 °F) for 15 minutes per 6 millimetres (1⁄4 in) of thickness, and does not significantly shrink or change shape during the process. Despite being called "clay", it generally contains no clay minerals. Polymer clay is sold in craft, hobby, and art stores, and is used by artists, hobbyists, and children.