A Bookbinder can be a number of things: Yes, they, we, bind books, but what does that mean?
For me it is two things:
Repair of broken books using traditional methods and the same or similar materials depending on cost and availability - and the wishes of the book's owner. Current thinking is to retain as much of the original as possible respecting the whole, as a book assumes a cohesive shape through time. Repair is what's required, not a makeover.
It is important to note that I do not do gold tooling or title label blocking, however I can order the latter from a bookbinder who does have this all-together-different body of equipment.
Making books/journals for personal travel or exhibition or sale in gallery/shops, or to commission. My preference as can be seen is a no-glue in the spine approach, which means the book lays flat. I tend to use 140gsm cartridge, or watercolour, or a harlequin mix including papers for pastels or charcoal, and Khadi cotton papers for the ends.
With raggy leather covers they become artefacts unconstrained by the expectations of a rigid book. I have recently become bewitched by the Dartmoor organic felted sheep wool purchased from Bellacouche in Moretonhampstead, which I use for covers instead of leather. But, clearly if being commissioned the client's preference is paramount.