I love my daily and weekly planners, and I was searching for a way to have the planner open on my desk for viewing. I also love gridfinity, and have a desktop system with various accessories. I found this beautiful book holder, and added a gridfinity (with magnets) base to it. I also found that while it fit my Hobonichi planner, my thicker Jibun Techo 3 book set with cover was too thick. So I added another size.

Check the thickness of your book first (especially just opening the first or last pages, not just opened to the middle) to choose which option best suits your needs.

small size:

large size: