I drew this manually in Windows Paintbrush, mostly by copy-and-drag.
I’ve named it “superknot”, but actually the shape it represents is a topological loop.
It’s a fractal generated in an L-system-like manner, replacing corners and unit edge pieces at each iteration with corresponding schematic drawings of a segment of tangled string that fills a unit square.
Feel free to use for any purpose.
You are welcome to add your thoughts.