Animation techniques and effects from the classic era. For more vintage movie geekery, check out my Old Hollywood Special Effects, and my Early Color Film Processes posts! (And while you’re at it, take a look at my art blog, why don’t ya?)
Just to highlight how important these were: many of these techniques have modern day digital equivalents that, while they’re now faster, are often very similar if not identical to their ancestors.
xerox was my favourite.