Here is an interesting video showing after WW 2 how all equipment is salvaged. At the 7:00 mark shows scrap planes being melted down and cast into dinner plates. When I first started casting I did the same thing as in the video melting very long pieces of aluminium in a charcoal furnace.
I own a 1930 Austin Seven special built in the 1950s. The student who built the body is believed to have used the aluminium skin of a Spitfire that was being scrapped at a local RAF base.