From my notebook...

Vibrant Play Dough
Combine
1 c. flour
1/2 c. salt
2 tsp. cream of tartar
1 c. water
4 tsp. baby oil

Cook over medium hear, stirring constantly until the mixture forms a ball and pulls away from the sides of the pan. Cool and then knead until smooth. Divide the dough into 4 portions. Put on rubber gloves and then pour about 2 tsp of liquid watercolor into each ball. Knead until the color is evenly distributed. Store in an airtight container and put in the fridge for extended storage.