Well, "oddly shaped" means it has to be convex, as a magnifying lens has to be.
It could be plano-convex, or bi-convex, anyway one side ad least must be convex.
More, the container's shape must allow the thin cilinder to be extracted from it, so it must be a open one.
The pan is flat, melting hot glass on it should just produce a flat glass, although it's worth a try-out.
What about the cooking pot? It's worth a try-out too.
Looking at the final proportions of the magnifying glass the lens has more the width of the glass of water, but you can't pour hot glass onto cool glass, they would melt together.
Maybe a refrigerating cloth in the inventory is advisable.
But the real question is which work to do. There's nothing which has directly to do with "cold". Many have to do with water, but the next step has clearly to do with water, so...? :hmpf: