Last May, I posted about an old cash-box I found in a second hand store for $4 that I'd planned to use as a mini easel & plein air box. I dusted it off and brought it out for Leslie's 30-day exercise. After using it today, I will make a tray to lift the area to use as my palette and give me a little storage under the palette. That may have to wait until after the challenge!
I did cut a leftover thin board (sorry it is black so a bit hard to see) that came with a frame I bought, but a thin piece of Masonite would work. The board was a little too large for the box, so I but off a piece about an 1" wide and glued along the bottom to give me a lip to anchor my canvas board which I attach using tape on the back. That just keeps it in place until I'm done. The extra board isn't necessary, but I like it because it helps both to raise the canvas boards up out of the hinged area and makes it easier to handle the wet canvas. So far its working like a charm.