My Astronomy Log / Journal is peppered with small very simple drawings trying to show what I am looking at or writing about. They may be stars, planets, or even equipment.
I have always planed on getting more into astronomical sketching. I have had the book Astronomical Sketching A Step-by Step Introduction for a long time now. It is part of Patrick Moore's Practical Astronomy Series.
One of the things that I have in mind to do is a series of drawings about O'Neill's Bridge (on the moon). I was studying it a few days ago from different sources and it is absolutely fascinating. It would be cool to see at least 3 renditions. One of what is there and at least two of what was thought could have been there like a natural arch and a constructed bridge.