Grafix Incredible Art Board, 16 in x 24 in

I've used this board for a while now to stretch watercolor paper and am happy with its performance. A regular office stapler can be used to staple your paper down. The board is sized for a standard half size sheet of watercolor paper, you can also cut it in half with a utility knife to have two quarter size sheet boards (which is what I did). It's also very lightweight.

Walmart's price was identical to what I found elsewhere. Like my other options, the product was not available in store. I picked Walmart because it did not charge for shipping.