A fabrication shop I used to work at did a order of 20 louvered doors for this one air conditioning/heating company for some custom application in a new building. After we finished punching all the louvers, they called back and said their engineer had given us the wrong dimensions for the flats and they could not be trimmed to the correct size. So there we sat with 20+ 27x51" sheets of 18ga. with a bunch of louvers in them. I kept a few for myself, gave some to a couple of brothers of mine and the AC/Heat company scraped the rest. Ya got a good find there.