Trying out some triangles this week.
I think a gentle cascade of colours down each column could look interesting… or maybe just alternating between 2 colours – dark, light, dark, light. If you could find 12 shades of the same colour, you could go shade to shade, from darkest to lightest. (The design is a little lopsided: the bottom has 12 layers per stack, whereas the top half has only 11. Oops.)
This quilt design could be made from half-square triangles (and flying geese, if you want to save some seams) and rectangles, and a few sashing strips between the columns and across the middle. Simple.