This is the one I used: http://www.onehundreddollarsamonth.com/diy-homemade-flock-blocks-for-chickens/. Pretty easy, and easy to modify with whatever dry stuff you have on hand. I left out the oyster shells (because I didn't feel like walking out to the garage to get it) and the spices. I did grease the sides of the baking dish with cooking spray, just to make sure it didn't stick. It came out really easily once it was completely cooled. A half-recipe nicely filled an 8x6x2 casserole dish I have, and that block easily fit into the square squirrel feeder I have, which I hung inside their coop. They've been pecking at it almost constantly since I put it in, so it must be good. I should probably take it out for a while so they eat more of their normal feed!
