Something I haven't done in YEARS. I mean, not since I was in school, so, like, 1990-ish.
A black & white drawing shaded by crosshatching. This is the kind of thing I would have done on the back of a math test while waiting for the teacher to demand we hand the tests in.
I did this in Krita but it was very much like the old days of using a ballpoint & paper. I enjoyed doing it.