In 2016 I was hired by Harry and Abrams to create mock-ups for them to use at trade shows. I would take "blanks" and then craft covers and sometimes interiors for them. Each project was a laborious task sometimes taking 3 to 4 hours to complete one book. Here are some examples.
Abrams Mock-Ups
Published:

Abrams Mock-Ups

Trade show mockups

Published:

Creative Fields