The Art of Cuphead (published by Dark Horse Books ) details the 1930s hand-drawn animation process:

Several versions of the book have been uploaded to public sharing sites. These are often used for previewing or offline reading, though availability can change:

The Art of the Cuphead Show - The Free Library of Philadelphia - OverDrive. The Free Library of Philadelphia - OverDrive

: Offers a limited preview of the first 50 pages for quick viewing. Content Highlights