Mix dry ingredients: Combine flour, salt, and cream of tartar in a pot.
Add wet ingredients: Mix in water and oil.
Cook the dough: Heat over medium, stirring until it thickens into a ball.
Cool and knead: Transfer to wax paper or a bag. Cool slightly, then knead until smooth.
Add colors (to use as sprinkles and frosting): Divide dough into balls, add food coloring in bags, and knead inside.
Store: Keep in airtight bags to stay soft.