Is There a Terrestrial Origin for the Aluminum Sheets?

It looks like the slitted sheets that art received are likely serpentine cooling fins from a car radiator. They've either been flattened out or they were never bent into the final zigzag s pattern. Art also receives scrapings allegedly taken from the underside of the roswell craft. Does that mean we should set aside these additional parts and conclude that they also have a terrestrial origin?