Since I contributed a comment to this thread earlier, I thought I'd give an update.
I have one very serious feather picker. Flo has a fixation on plucking feathers out of anyone in her vicinity. She eats them, too. I had tried feeding her extra protein, and even segregating her in the rooster pen. I finally took pity on her and returned her to the hen pen because she had become fairly denuded, herself, from the serial rape.
So I decided to approach the problem from the opposite end: protect the victims. I made saddle/aprons and installed them on all of Flo's victims. Then I bought some pinless peepers and installed one of them on Flo. (I had to buy a box of 100) 
Flo still manages to pick feathers, but it is greatly diminished because she can't see straight ahead. The thing that's really slowed the feather picking down is the saddle/aprons. Poor Flo sometimes needs help getting through the pop hole at night since she can't see where she's going, and she can't enjoy the hanging treats, but it beats getting eaten.