Plastic you colored with magic markers and put into the oven. The big plastcic pieces (cars, florwes...) would shrink down into think smaller pieces. Plastic that you would color, cut , and then put into the oven and it shrunk. It was a sheet of plastic that you colored, then baked in the oven. The sheet would reduce in size due to the heat and the end result would be a miniature colored item. Little sheets of plastic you would cut "designs" from like Key CHains, Boyfriends names, you wuld color with these little pens and put them in the oven and bake them on a coookie sheet! The Shrinky-Dinks I remember were not made from a flat piece of plastic. It was a goo that you mixed up and poured into molds. They made silly-looking birds and things, complete with feathers. Once the mold had congealed for a few minutes, you pulled the molding apart and stuck the "sculpture" in the oven for a short time. They shrank from about 5 inched to 2 inches, and hardened into a porous chalk-like substance. I no longer have the blue bird my cousins made for me with this toy. Bummer.