Some years back I did some IT work for some old school media companies. One outfit did the opening credits for Gone With the Wind. The “3d” effect for the title was done with layers of paint on a sheet of glass.
That piece of glass would probably be worth one heck of a lot of money today, except that back then flat, clear glass was pretty valuable so they shaved off the paint so they could reuse the glass.
Margaret Mitchell was my 2nd cousin.