I have a futon. I ordered covers for them from eBay about 8 years ago. I don'know if the guy still sells them, but he had a large selection of colors and the fabric is like a microsuede. I ordered raspberry and dark brown and switch them out and they look great. I have used them constantly for 8 years. They have taken a beating and they still look new. There is a polyester backing on them and it protects the mattress from stains. If you want to make your own, you would probably measure the length and width and thickness of the sides to make something that looks like a big pillowcase, without the ends sewn together. Then, measure the length and width of the ends and add into the width what you think you'll need for a zipper casing. Then cut that in half and sew a long zipper in. Now sew the zippered ends to the big cover Don't forget to add in seam aowances to your measurements. Amazon sells log zippers. Choose a fabric that will protect the matress from spills if possible. You can also buy a can of Scotchguard.