I've started a new large sized Moleskine watercolor sketchbook and I plan to just have watercolor charts and various mixes in it. It is a huge book, 16 1/2" x 11 3/4"/42cm x 29.7cm, especially when open. It's a bit awkward to work in, but each page is so satisfying when complete. Prints will be available for purchase.
This page has Hansa Yellow Light, a cool yellow, and New Gamboge, a warm yellow, mixed with Transparent Pyrrol Orange. The original color is in one of the most right or most left tall rectangles. The mixes between the two colors move gradually towards the center of the page. The smaller boxes below each tall rectangle are with that particular color with some water added and then more water.