Here's my post about the playdough we made.
http://www.webmomz.com/resources_playdough.shtml
What You Need
1 cup flour
1/4 cup salt
2 T cream of tartar
2 Tsp food coloring
1 T vegetable oil
1 cup water
What to Do
1) Mix the flour, salt, and cream of tarter in a medium pot
2) Add water, food coloring and oil
3) Stir over medium heat for 3-5 minutes. Don't worry if the mixture looks like a lumpy mess; it's turn into dough
4) When the mixture forms a ball in the center of the pot, turn off the stove and let it cool. Then take it out of the pot and put it onto a floured surface. Knead it several times.
5) Store in the Ziploc bag or airtight container in the fridge.