If you are looking for a cheaper alternative to store bought bases. Go to your nearest x-ray clinic and ask if you can have the protective sheet that is in every pack of blank x-rays. All you have to do is cut to size.

I also buy the thin foldable plastic cutting boards at discount store, and cut them to size. Usually I can get four in a pack for $2.50 or so. Easy and washable.

TY.. great ideas!

Go to your local sign shop and ask for their scrap sign plastic. Lots of times it's freeeeeeeee!