In top of a double boiler, thoroughly mix 1 cup cornstarch with 1 pound bicarbonate of soda. Mix in 1 1/4 cups cold water and stir constantly over medium heat for about 4 minutes. When it is like mashed potatoes turn out onto a plate and let cool covered with a damp cloth.

After cooling, knead like dough, don't knead it all at once. Put unused portion in a plastic baggie, so it won't dry out, and just knead the part you are going to use. If you knead in a few drops of white glue (like Elmers) it will give it extra strength.

Mold your shapes by hand or cut with a cookie cutter. When you have the shape you want, dry the piece for 36 hours (or until it's really hard). You can paint with tempera paint, and after that is dry coat with shellac for shine and protection.