Here I am- totally red butterfly art journal - entirely handmade, with leather-like cover and water color papers (Canson) inside. I am closing with elastic, small leather strap and a charm. Who wants me? :)
12x 16cm (4,72"x 6,29"), 12 pages (24 in total).
As it is a butterfly book, you can take out the pages at any moment, work with them on flat surface, arrange them to your liking and of course- add more pages if you'd like.
The Butterfly art journal with watercolor paper is the yin, to your yang. You've found what you're looking for.