how to make your own gluten-free flour mix

Here are a couple of g-free flour mix I use for things like muffins, waffles and crumb cakes. 

Gluten Free Flour Mix #1:
200 grams rice flour (ground superfine is best)
100 grams sorghum flour
200 grams quinoa flour
100 hazelnut flour
100 grams corn flour (non-GMO)
150 grams tapioca flour
150 grams arrowroot flour

This is a very nice high protein flour mix with a lovely taste because of the hazelnut flour. 

Gluten Free Flour Mix #2:
300 grams superfine brown rice flour
100 grams almond meal / flour
200 grams quinoa flour
100 grams corn flour (non-GMO)
150 grams tapioca flour
150 arrowroot

Yes, I used a scale here.  And it makes about double what you need for most recipes (store the rest in the frig to use the next time).  But you can approximate this mix by using with the following formula:

3 cups of gluten free baking mix = 2 cups gluten-free flours and 1 cup starch

2 cups of any of the following flours in combination (use at least 2 different flours):
Brown Rice

1 cup of any one of the following (or in combination):
Potato Starch
Tapioca Flour
White Rice Flour

Experiment with different flours and have fun!  If you want a g-free flour mix for a cake or a baked item with a finer crumb, use equal parts flour (still use at least 2 different flours) and starch.