Not easy stuff. Here is some sort of brush strokes explained: https://gorillasun.de/blog/simulating-brush-strokes-with-hooke's-law-in-p5js-and-processing

also, here is a collection of ideas: http://www.generative-gestaltung.de/2/

Wow! That's a nice effect. I see what you mean by not easy. But it gives me some ideas that might be easier to do.

Thanks for the resource pointers!