The aluminum-alloy 'skin' of the Lunar Module that carried Neil Armstrong and Edwin (Buzz) Aldrin to and from the moon's surface in July 1969 was only 1/12,000th of an inch thick, to save weight. That's about equal to three layers of aluminum foil.
Source: Tom Kelly, former Lunar Module Engineer, on the PBS-TV show 'To the Moon' ('Nova' No. 2610), first broadcast July 13, 1999.
(c) Copyright 2001. The Christian Science Monitor