Ok, lets be honest. You probably thought you would not see something like this on here. ;-)
I made this a couple of days ago in about 20 minutes out of swim suit material. It took about a yard and I already had it on hand. Hooray for using up the stash! I saw the cover idea over here but did not want to pay that price so I decided to make my own.
It's basically a rectangle, open on one end with the drawstring. The other end is sewn shut and has the handle inserted at each corner. The material is 60" wide and went around my 65 cm ball just perfectly.
So why the cover? First of all, that strap is handy! If you have ever taken one of these things somewhere and had it go running away across the parking lot, you know what I mean. Most people know these balls as exercise balls but I know mine as a birth ball. I am working toward my CE/D certification through Charis Childbirth right now and have been learning that these balls offer really great comfort techniques during labor. My ball is made out of rubber that is not very smooth and has ridges on it. This is not comfortable if you are leaning or sitting on it. A cover makes it smoother and is nice for clean up too. Hopefully I will make a few more in case they get dirty and so I can carry it in one, and switch it out for a clean one at the birth place :) More information here on how it is actually used during labor if you are interested. You learn something new everyday right?