I have an upholstery shop. Go to your local shop and buy a product called chip board. It is a little thicker than say, a cereal box. Cuts easily and you can write on it. This is what I use, and it is 26x38 inches. Gives you plenty of room. Shouldn't cost more than .75 to 1.00 @. But I do like the idea of plexi to see thru. Great idea JL