dh goes to our local home depot... it's 1/8 " thick by 4x4 sheet.. you use it for bottoms in dressers and etc.. its a dark brown color.. I don't know the term name for it. It's 2 bucks and change for a sheet.. dh cuts it into about 16 pieces.. so very cheap and it is soooo sturdy.. you could use it as a defense board if need be!!! lol
anyways.. that is what i use in mine.