Originally Posted by
ksdot417
I make a fabric sleeve and insert a piece of foam core board and then sew it shut. It fits great in the corners and can be removed if you need to wash it. I've also used the plastic canvas.
I have had wonderful luck with this method. Being able to remove it for washing is super. I can take the foam board out and just wash the sleeve. Had a problem with things sliding under it so use a spray glue when I put it in the bottom.