I looked into this a lot and decided it's way more effort and expense than it's worth. You have to find sources of all the various grains, have places to store them separately where they won't spoil or draw rodents, grind it all up (unless you choose to feed whole, which can lead to them picking out just what they like, plus the supplements won't stick unless you add oil), and the vitamin/mineral powder only comes in big bags, so it would go bad before I'd use it with my flock of 12.
Honestly, I wouldn't recommend it unless you have enough birds to buy in bulk and use it fast.