I am going to try to document all the different accessories and components used to create a compact studio for quick studies and outdoor paintings. I started with a cigar box given to me by my uncle. This Hemingway cigar box has a 1/2" recessed lid. For the palette I recycled glass from a 5x7" picture frame that I secured with canvas offset clips like this. Underneath the glass is a sheet of grey-toned paper. Another option would be to paint the backside of the glass in a medium grey acrylic. To finish it off, I nailed in a couple of the wood pieces that came with the box on an angle to streamline the look.
You will need to clean up your glass palette after painting. Yes, it's true! An easy way to do that is to use a razor blade to scrape the paint right off. I created this razor blade handle/stand combo out of polymer clay that I baked and then sanded down for a nice smooth finish.
P.S. Right now I have heavy weight striped paper straws across the top and bottom used to transport the painting panel. I might switch to a more stable permanent solution shortly.