This is probably the oldest making-of I’ve ever seen. It’s actually kinda weird to see a making-of that predates the invention of television. I’m assuming this was show before a movie alongside actual cartoons, newsreels, etc.
The Making of a Popeye Cartoon (1938)
https://www.youtube.com/watch?v=fkKjRr_zlxw&list=PLYn2a0e2FVIJ66EP8vMU64l-kIhHU9zg7&index=15&t - from the Margo Burns YouTube channel (6 mins long).
The blurb:
“How the Fleischer Studios made the Popeye episode Aladdin and His Wonderful Lamp.”
Spider-Man On The Move (1981)
https://www.youtube.com/watch?v=S2qGPQGDmMg&list=PLYn2a0e2FVIJ66EP8vMU64l-kIhHU9zg7&index=17&t - from the Josh Hadley YouTube channel (26 mins long).
The blurb:
“Documentary on the making of Spider-man and His Amazing Friends. Hosted by Stan Lee.”