was just wondering, because if it were me and each will be used 2x then I would probably just do 2 blocks of each color combo(2 of the same). then play with the layout once they are done. If you do go bigger then you would have 80 and then it would be a even number and all your blocks would be included.
you could also use same 2 colors but switch the background fabrics around when making the second block.
did I make sense?? hope you understood