I found several (some I had not heard of before) books about and with typewriter art online, at the Internet Archive. They are a lot to look through and I’m glad someone else had the job of digitally preserving them, and I’m really glad they did!
Typewriter Art by Alan Riddell
Fun with Basic Keyboard Graphics
George A. Flanagan
A Treatise on Ornamental Typewriting
Fun With Your Typewriter
How to Make Typeys