I've been doing wood shavings, simply because the bags they have at TSC are cheap. But they do kick it out alot and I have to keep adding more. I'm thinking of cutting some outdoor carpeting to set in the bottoms of the nest boxes in addition to the wood chips. They have those cheap doormats at Home Despot for less than $3 each that I've cut up for other projects. I don't mind using them until they're trashed then cutting up more at that price.
Lol, I use straw and shavings for their boxes, but they also kick most of it out. Eggs end up getting cracked when they hit the plywood underneath. Like the outdoor carpet idea, i was running with using 2 layers of 1/8 rubber under the nests.