Japanese style stab bindings
This binding style is great if you want to create a book for watercolour, or to have a no adhesive binding which is easily fixable, and takes adding and removing pages well.
The pages can either be a group of loose leafed pages, or if you are using paper that is thin enough that ink or paint bleed through is a concern, fold the paper once, but have the folded edge on the outside of the book, the foredge. That way, the paper has an internal layer to soak up excess ink or paint.
Collate your paper, including your decorative paper you are using as covering material, and make an even number of holes equidistant on one edge. Use a colourful thread to go in between each of the holes, making sure that the thread goes in a hole, then around the nearest paper edge, back into the hole before moving to the next hole. On the corner holes, go around the edges on the side and the top edge of the paper. For the bottom corner, side and bottom.
When you've gone through each hole, and arrived where you started, tie off, and push the knot into one of the holes.
You can add extra decorative holes not in line with the first set, to add to the design and give more stability on the edges.
The book Japanese Bookbinding by Kojiro Ikegami is the standard textbook for these structures, and they give lost of variations.