I looked your explanation of configuration space up when I was having trouble understanding it in the No-Nonsense Classical Mechanics book recently authored by Jakob Schwichtenberg. His book is basically a good book that mostly does what its title implies , but I thought his explanation of configuration space was very abstract and hard to understand. You cleared it up for me. Your explanation of Configuration Space is the no-nonsense explanation of CS, not his. Thanks for your work. Regards
PS: I enjoy your homemade diagrams! My opinion is don't waste your time learning a CAD package even if people complain. If the don't like it, rather than complain, they should volunteer to draw them for you.