Images which go with my Extra Fine Nib Ink Review (EFNIR) posts. (Reviews of inks using only a Japanese EF nib.)
A file name with no code-letter in the file name, just the ink name, is a screen capture of the review from the video. A file name ending in a capital "Z" is a "zoom" photograph taken with a USB microscope.
These doodles are mostly for stress relief for me plus training my hand after the time of many wrist inflammations due to strain. They were made from 2016 to now.
When I begin such a doodle I have no plan. All I know is that it will follow some rules how the edges are connected and what angles are allowed. So the doodle would just grow like a crystal. As you can see they also may vary in symmetry and number of axes - which also might be broken sometimes in favour of other patterns. That's what I call them, "Muster" - German for "patterns".
I usually do these on 4-5mm squared paper. Some were made on a thin hexagon isometric 5mm grid or dot grid. Some are made colourfull by pencils including ones in neon and metallic, markers or just plain ink.