I made 2 of my own big boards EASY PROJECT. I bought a precut 24 x 48 inch piece of lumber at the local home store. If they dont have the right size at your store, they will cut a piece of plywood to whatever size you want. I used 1/2 inch thick. Brought it home, stapled batting and a cover on my first one. For the 2nd I got a bit smarter and made the top with an elastic casing. That way I can slip it off to wash it occasionally. I find the weight of the wood/fabric makes it stay just fine without any additional boards. I have been using these for over 10 yrs without any mishaps.