It's easy to make a "quickie" cover by cutting a square of fleece or similar material - even tee shirt jersey material works well - about 3" inches wider than the widest point of your face cradle..... then, here's the hard part .......... cut a slit up the middle of one side......... then you're done.
If you want a form fitting one, lay out a cradle cover you already have and give it a generous outline margin and cut from there.....
.... that's the advice from the cheap seats over here...........
J