Sometime in the 1980s (who the hell actually knows when), a much younger David Letterman had a guest on to demonstrate the art of foley (the post-production creation of sound effects). 

His guest was John "Jimmy" James MacDonald, who was the head of the Disney Sound Effects department and was also the voice of Mickey Mouse from 1948 to 1977. 

He demonstrates many of the objects, some of which he built himself, used to create the sound effects of many of Disney's early animated classics.