Here's a little piece of code/art that's been on my mind for years, that I never got around to attempting. Luckily somebody else did it first and shared the source code, which I just stumbled across.
Unlife runs Conway's Game of Life backwards so you can create a start-state that eventually produces an arbitrary desired state.
Created using unlife, golly, giffer.py plugin for golly, and gimp.
https://quinapalus.com/unlife.html
http://golly.sourceforge.net
https://github.com/conwaylife/giffer