Many of my books are altered hard covered books that I cut the pages out of. The fun part is using a wide variety of papers for my signatures (such as natural dyed papers, scrapbooking paper, maps, children's' book pages, tissue paper, fabric, brown paper, etc.)
I create my signatures with interest before I sew them into my books using a hidden spine.
My favorite way to cover my books is with fabric and I usually print an image onto fabric for the center interest.
I use my books for sketching or art journaling or I just give them away. I have art journal tutorials on my YouTube Channel that you can watch. I also have handmade art/junk journals that I sell in my Shop.