DIY: Cup for cup, make your own Gluten Free Flour Mix! 1 C each of white rice flour, coconut flour, oat flour, and tapioca flour/starch, 1/4 C cornstarch, and 3.5 tsp xantham gum. Mix well and store in airtight container. Use cup for cup in any recipe that calls for flour. From YourHomeBasedMom.