My copper and zinc laps are both 1/2inch thick and rather heavy, so storage is easy. They dont require any super flat spot for storage. Currently I have them in gallon ziplock bags and then in the cardboad boxes they arrived in. Someday I’ll upgrade to stackable lap containers or a rack of some kind.

the difference between them?….Im not really sure. i got them both for a nice price from JDGems in Vietnam. I use copper for 8k and zinc for 60k because thats what i read online somewhere. I imagine copper holds the corser grit better, but thats speculation on my part. sorry i dont have a better answer for you.