Just cut you a board about 12" or 14" or wider and from whatever the length of the roost is. secure under the roost about 8"s or to your liking! Personally I would make it like a box ( with raised sides) and put an inch or a couple of inches of sand in the poop board to help with cleaning! the poop will be easier to clean in the sand with just using a kitty litter scoop!