Bookbinding
A personal hobby of mine, bookbinding has been a long-running exercise in prototyping. All of my books begin as loose paper and end as leather bound tomes that might look at home in the Hogwarts library.
The process goes as follows: fold and sew the pages together, glue the spine, attach the bookmark, sew in the head and tail bands, construct and attach the covers, glue on the leather, carve in any designs, dye, and seal. Prototyping has been done to experiment with different ways of attaching the covers, different sewing techniques, and more.