One person on the AZ thread uses AC filter material and it looks really nice. She just cuts to size and rinses it out to clean it. I've been using herbs- lots of rosemary, lavender and lemon grass. I cut big bundles of herbs and lay them in the next boxes with an old Manila file folder as a liner. When dirty I can lift the file folder and dump everything all together. The mix of herbs smells so good! I added a little pine needles for extra cushion now that I have more hens laying, just to prevent eggs breaking because so many hens are going in and out of the nest box all day long.
I have lots of herbs and huge pine trees so trying to use free nesting materials. The rosemary, lavender and lemongrass make the coop smell really nice, plus I need to trim back the plants every so often, anyway. I've heard they are supposed to repel lice and mites, too.