What are some waterproof "flooring" options everyone likes? Unfortunately my female bunny is not super good with the litter box, particularly poop and more irritatingly, sometimes pee. So I'd like to put down something water proof for the floor of their pen. I tried a vinyl table cloth first but the male chewed a big hole in it within two days. Was thinking about a tarp next but I'd like to hear more possibilities as well, especially what's worked for chewers and diggers.