This system was originally created with my (back then) 11 year old daughter. We sketched around with a pencil and envisioned a tile-based pattern system that we could produce as physical stamps. Which we did as well, by the way.
We started with 5 straight lines and then went with the most basic variations we could think of.
Then I had to play around with it using my favorite procedural design tool pattern nodes.
The setup became quite complex on the first look — see for yourself below.

Available as unique loop animations on foundation.app here: https://foundation.app/collection/kirapt01