used like cat travelling crates for nesting boxes, old car mats for lining the bottom of wooden nesting boxes makes cleaning a snap, on the same line a industrial all weather entry mat for covering the coop floor perfect fit 4 by 6 super easy to clean, not super original but using dog kenneling...
freeze some water bottles make sure cap is on tight mine lay on the frozen bottle to help cool them selves. when it all melts I wipe it down and refreeze I have a few to cycle through
it is basically poop that they do that they re eat and get a lot nutrients from if u have a sick rabbit lots of times a vet wiil have u take it from ur healthy rabbits and give to the sick one to eat