1. Combine 1 cup of water, 1 tablespoon of vegetable oil, 1/2 cup of salt, 1 tablespoon of cream of tartar, and the food coloring of your choice in a saucepan and heat over medium heat until warm. The cream of tartar in this recipe ensures that this playdo+ugh will keep up to six months in an airtight container, so don't skip this important ingredient -- it's available in the spice section of the grocery store.
2. Remove the saucepan from the heat, and add 1 cup of flour to the mixture. Stir well, until the flour is fully combined into the liquid ingredients.
3. Turn the dough out onto a clean, non-floured surface and knead until the dough is smooth. Allow it to cool for about 10 minutes.
4. Divide the playdough equally into the number of favors you need. (This recipe makes about 4 fist-sized balls; double or triple it if you need more.)
5. For each piece of dough into a ball, and place each one inside a jar or any container with a tight-fitting lid. Attach and close the lid, label the top with each guest's name. (Want to get the kids involved? Have them decorate the labels for the lids!) Tie a colorful ribbon around the neck of the jar for an added touch.