It's actually pretty easy and you probably have everything you need already.
Here's the recipe I used...
1 Cup Flour
1/2 cup salt
2 tbsp oil
2 tsp cream of tartar
1 cup water
food coloring (where rubber gloves so you don't stain your hands while mixing)
Heat the oil in a pot. Remove from the heat and add food coloring and water. Stir in all other ingredients. Continue to cook over low heat until mixture is firm, about 4-5 minutes. Remove from heat, and set clay mixture on wax paper to cool.
Store in an airtight container.
Note... I didn't use the food coloring for the batch I made. We left it white and added glitter until we thought it looked pretty.
We started to make these snowmen with it. Can't wait to finish them.