What is tomecraft? I first heard the term years ago as a way of describing the creation of fictional grimoires and books of forbidden knowledge. It covers the entire process, from coming up with an initial concept, through writing the text and finding or making the artwork to illustrate it, down to the final assembly of the book itself. In many ways it's the pinnacle of Mythos propmaking.
The most daunting part is the final bookbinding. Turning the individual pages into signatures, mounting them into a page block, and building the cover is an intimidating undertaking. I say that from personal experience. Thankfully, their are artisans like Dennis at Four Key Book Arts willing to share their experience and knowledge.
David Stay was kind enough to bring this video series to my attention. It starts with the decision to rebind the core Dungeons & Dragons rulebooks into a single massive tome and then goes through the entire process of breaking them down, reassembling the pages into a single block, and binding the whole thing in a beautiful leather cover.
It's a long process spread out over four videos. If you have any interest in making even a modest tome I highly recommend taking the time to watch the whole thing. There's something both relaxing and inspiring about watching an expert at work, and Dennis does an excellent job of describing each step of the job.