Ok. I made playdough. It went down really well with Jack. Really, really "Oh my god she's covered" well. Here's the recipe.
1 cup of flour
1/2 cup salt
Food colouring
1 cup boiling water
1 tablespoon cream of tartar
Put everything but the flour into a saucepan and heat. Stir the mixture until it forms a ball. As it cools it will become less sticky. After it has cooled knead it until it is smooth.