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!
Alan Riddell
Typewriter Art by Alan Riddell
Bob Neill
Bob Neill’s Book of Typewriter Art
Bob Neill’s Second Book of Typewriter Art
Julius Nelson
Typrinting
Artyping
Artyping: Second Edition
Artyping: Third Edition
Stylebook for Typists
Typewriter Mystery Games
Winnifred Nichols
Fun with Basic Keyboard Graphics
George A. Flanagan
A Treatise on Ornamental Typewriting
Madge Roemer
Fun With Your Typewriter
Nathan Krevolin
Art Typing
Underwood
How to Make Typeys