How do i make soy bean powder out of my soy beans?

I want to use the powder to store instead of the beans. That way i can just use the powder to make the milk. Is there a way i can make dry soybean powder and use it to mix with water and make the milk?How do i make soy bean powder out of my soy beans?
Soy bean powder is baked. First you must reduce the beans to flour and then bake it. But it will still contain more material than powdered soy milk.