1 c. flour
1 c. salt or baking soda
1 c. cornstarch
1 c. water

Mix all ingredients and cook over a medium flame until thick. A drop or two of glycerine can be added at this point but is not essential. If the mixture is too solid, add some more water.

Divide and add food coloring to each part. Keep refrigerated in plastic containers. This will keep workable for a while and won't do any harm to hand-to-mouth children.