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DAS bookbinding - lots of bookmaking methods, explained in detail.
Annesi Bindings - mostly casebinding, and other useful things.
Dan Siebel's kettle stitch tutorial -short video on how to do a kettle stitch. Filmed up-close.
Tumblr links
Renegade Publishing - a group of independent fanbinders. They have a discord (though it's 18+) and answer binding related questions on the blog.
Armoredsuperheavy - founder of renegade publishing. Maintains multiple docs about the full process of making a book.
Hedgehog-moss's post about bookbinding - beginner information, links to resources
r/bookbinding - a large community of people. You can share your progress, ask questions. You may get criticism though. Expect brutal honesty.
Other links
Alternative bookbinding supplies - We don't all have the correct supplies lying around. It's fine.
How to: Headbands - article about sewing headbands.
Don't forget to use acid free materials! Acidic paper/glue decays with time, causing your book to turn yellow and fall apart. PVA and weath paste are commonly used adhesives.