This is a great flour mix that can be substituted cup-for-cup for wheat flour. I make a big batch of it and it stays well on the shelf.
6 cups rice flour
(there will be a taste difference between white and brown rice, you will just have to experiment with what you like)
2 cups potato starch flour
1 cup tapioca flour
Mix well together. It does leave a slight grainy texture in baked goods.