/ic/ - Artwork/Critique

Are there resources on how they made anime in the 80s/90s? I mean from a technical point, what paper they used, pens, painting techniques for fore/background, how they were able to color characters so smoothly, etc.

I know the use of cels (some form of plastic?) for characters, then how did they smoothly color them? How does drawing on cels differ from paper?

I've heard that they used watercolor for backgrounds, so what kind of brushes and paint brands (or whatever) or canvas can you use to emulate that? And what about other techniques like gouache or whatever?

Even better if there are resources for dbz and related animes from the past.