I have most of my societies trying to build a nest together, which since they're in a homemade cage of 1/2" grid wirecloth, means shoving things through the mesh above and along one vertical perch branch over and over.
Maybe instead of giving them a nest, just put up some vertical branches or perches, a little cluster of sorts, and give them lots of orchard grass (hamster section of any petstore) and let them try to build it themselves. Will keep them busy much longer. If it starts to take on a real shape, then either give them feathers or knock it down so they have to start all over and don't pluck each other lining it.
I have given my societies and my zebras loose fake leaves and flower petals to work with, keeps them busy, and if they ever start to accomplish anything for real, the big ol' bad Nerien-wind blows through the cage and knocks it all down so they have to start over again. I am so mean to those little birdies.
But it works, is keeping those little psycho zebras busy, and now I have 4 males in with only 3 females and they haven't figured it out yet!
. Their bickering is minimal and they act more like a pair now. Its seems like they are trying to build a nest. They are shredding their sisal ladder and placing their own feathers on a high perch, which is nested within some fake foliage. I'm a bit concerned that they might resort to plucking themselves or one another, so I was thinking about giving them some coco fiber and a twine nest ball. What do you think??? I don't want to encourage anything that will bring out aggressive or territorial behavior. They are still alone in a large flight and will be for another 2 months. Thanks for your help... 
. The sad thing is, I just don't want to do the wrong thing for my boys 
. So I wont add a nest (or 2) because I don't want to risk either or both of them becoming aggressive/territorial toward one another. 
. We didn't actually see him pull a feather, but he kept going back to that area picking around with his beak. Of coarse I considered mites for a second, but I sprayed all of my birds and their cages/perches with AIL 1 month ago. I also considered that Ernie could have done it and now he's just uncomfortable...but Bert is the alpha of the pair. He looks perfect until he turns his head around and moves his wings to reach his back. I put coco fiber in the flight and all of the boys (5) are very interested in it. I'm going to keep my eyes on things, but I am considering dividing the flight again. I don't want the coco fiber to trigger breeding issues with my M/M stars or my M/F owls. As it is, Geri lays 2 eggs a week without having a nest/material in the cage. Any other suggestions??? I will add a heat lamp to the top corner in case Bert is cold... 
But once again, Mother Nature throws a monkey wrench into my peaceful bird room 
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. I still have your double decker parrotlet breeding cage. Plus the 2 black breeding cages too 
, fill one of those breeder cages with baby owls, then we'll just pick it up from you pre-filled. 