My local Menards (hardware store) has these brightly colored popcorn bowls. They are fairl thin, pretty big, and cheap at 97 cents each. I got some snipping shears and voila! Instant hidebox.

If you have a rack, I think one thing to keep in mind is weight. If you are using clay pots for example, and you add up that weight over 8/12 slots it could be a pretty significant force weighing down on your rack, i.e. rack sag.

Use your imagination

JonV