Tough Times for a 2-Year-Old

Found ourselves in Wal-Mart last night picking up a few grocery items when it occurred to our 2-year-old that he 'needed' new Play-Dough.  He was very insistent that he needed it, as a matter of fact.  How do you explain to a 2-year-old that Play Dough is not depletable?  You don't.  You simply tolerate the fussing, screaming and tantrum until it passes and try to tell him that you have a great idea - you will make him some homemade play dough and say it with as much excitement as you can muster.  He eyed his loving parents with expected skepticism but seemed pacified by the fact that he was still getting play dough one way or another.  I am including the recipe I have for it but would like to know if anyone has a variation on it or suggestions to make it even better - believe me, this child will know the difference between the trademarked stuff and the homemade stuff and he will point it out to me immediately!  Also, does anyone know if this is supposed to be all-purpose flour or self-rising flour?
Kid's Play Dough
2 cups flour
1 cup salt
1 tbsp cream of tartar
2 tbsp cooking oil
1 cup water or more
Food coloring
1.  Mix dry ingredients in large sauce pan.
2.  Mix oil, water, food coloring.
3.  Mix all together.
4.  Cook over med. heat for 1-4 minutes until it's not sticky.  Let cool and play with it.