Plasticine can be purchased online from Amazon. Plasticine is one brand name of a type of modelling clay that does not harden, even if heated. Other brands of this type of clay such as Plastelene and Permoplast, are available at Rainbow Resource. Michaels sells a brand of this type of clay called Plastalina.
Traditional, "real" clay is made out of minerals and air-dries but needs high heat to set it into a permanent shape. A number of different types of synthetic clays have been invented that have many advantages over real clay.
These synthetic clays can be separated into three categories. One type air-dries into a solid, permanent shape; Play-Doh is a well-known brand of air-drying synthetic clay. The second type will set into a solid shape if heated to temperatures achievable in a home oven; Sculpey is one of the more popular brands of heat-setting synthetic clay. The third type of synthetic clay never hardens,; Plasticine is the brand most commonly associated with this type of clay.
Plasticine was the first commercially available version of nonhardening clay, and it is commonly used for children's play. It was originally invented in 1897 and is a registered trademark of Fair Leisure Products Plc.