If you are using the glass bowls (Anchor Hocking) that I have suggested, you know that they are a little unstable when placed over the glass pie plate, either Anchor Hocking or Pyrex.
Now, Pyrex has a new pie plate, available at Target, which has a wide rim all the way around. The rim is sculpted. This wide rim pie plate, called an easy grip, fits perfectly into the All Season Solar Cooker and makes a great base for the 4 Quart anchor hocking bowl. Try it