In the same kind of ideas, there is also a mind blowing trick with "Kaleidoscopic Iterated Function Systems" which allows for a very compact code by folding space to create psychedelic fractals. https://www.shadertoy.com/view/tdcGDj (move mouse, and view associated video for more).
On page 60 "CONCEPT ART (FROM OTHERS)" there are some beautiful images this guy used as inspiration, but I can't find a link or reference to their origin.
