I won't lie. I spent the majority of my time in long-run commercial bindery and digital finishing. But, I have had opportunities to see first-hand many "craft" book binderies that produced exquisite, valuable hard cover products.
For many years, I had no clue as to what it took to produce a high-quality law book, Bible or museum-quality book. But I became gradually exposed to this world in trips to boutique finishing operations and through my association with the Hard Cover Binders Association (which is now part of the Book Manufacturing Institute). An enormous font of knowledge is Professor Emeritus Werner Rebsamen, who was himself a master bookbinder.
Becoming a "master" bookbinder requires years of apprenticeship and training, many times using tools that have remained the same since the 16th Century! The number of separate operations employed in making these products is mind-boggling compared to turning out magazines like Newsweek or People.
Let's take a brief tour. First, the papers used are going to be high-quality (and expensive). Instead of adhesive binding, the book block signatures are going to be sewn, typically with "Smyth" sewing, a technique developed in the 1870s and still used widely today. Unlike many hard covers, the back of the block is going to be rounded, which according to Rebsamen, reduces the stress on the signatures when the book is repeatedly opened. The rounding process used to be done by craftsmen using special hammers. But it's a machine process these days (as is most sewing).
The case is even more complex. Special board material may be used, and instead of paper, expensive cloth, linen or leather will be used to make the case. Wait, we're only getting started! Now we have to apply special touches to the case. The case may be embossed, it may need gold foil stamping. There aren't many machine vendors that make these systems. There's only ONE that I know of that manufactures personalized foil stamping systems. Antiquing is another process that gives the case an "aged" look. When I saw this being done at Taylor Corp. (now Balfour) in Houston many years ago, it was 100 percent manual, with an operator hand-rubbing the case with black ink.