We bought these huge pots from a Chinese grocery in LA's Chinatown about a gazillion years ago. We spotted them outside behind the store with all the used cardboard boxes, baskets, and other shipping crates. I think they charged us $8.00 each for them and were amused that we would want the containers left over from shipping 1000 year old eggs (they did have a funny smell).
two frozen discs
Mr. Cranky takes out the ice and turns the pots over and that is all it takes to preserve them for another year.
I know, I know, we could just turn them upside down before it freezes. Where is your sense of adventure anyway?
We keep a couple of the larger ones upside down permanently, the shallow depression on the bottom makes a perfect birdbath.