This is really not a sketch, and kind of silly, but I'm proud of myself damn it. Because I decided I would draw a library, a really high ceiling library with spiral staircases. Then I decided you'd be looking way up at the roof of the library. Then, perspective on spiral staircases blew my mind.
No problem, I thought, I'll look pictures up on google. NOPE, there are lots of spiral staircases but you only get two views - dead on and straight up or down them.
So as I doodled and tried to picture it in my head I came to the conclusion there was only on solution, build a model.
And thus with printer paper and tape, did I construct a model staircase just so I could take a picture at the angle I needed. And it was SO USEFUL, I mean it totally explained how the whole thing works! And now I have a paper spiral staircase.