1/2 cup rice flour
1/2 cup corn starch
1/2 cup salt
2 tsp cream of tarter
1 cup water
1 tsp cooking oil
few drops of food coloring (if desired)
Mix ingredients in a medium sized pan. Cook stirring constantly on low until mixture forms a ball and is no longer sticky. Pour out onto heat safe surface and knead until smooth and uniform texture. Store in ziploc bag.
Mixture tends to be a little more sticky than conventional playdough. But my son didn't care. Crayola Model Magic is gluten free, but this is way cheaper.