United States Navy Foundry Manual
This book was a navy field manual designed to allow naval personnel aboard ship to reproduce vital parts without having to wait on resupply. It has a huge amount of information, but is written so that even a squid can understand it.
I find this book to be a huge help in designing molds for casting metal parts in my home workshop.
Not only does this book cover mold making, it also covers metallurgy, types of foundries, and a lot more.