Several years ago my guild collected orphan blocks and I got nominated to piece the tops. I sorted the blocks by similar colors or themes (like flowers), picked some sashing that went with the blocks. I used varying widths of sashing since the 12inch blocks were between 10.5 inches and 13 inches. Then I assembled the blocks with a narrow strip of another color of sashing. They looked great -- some were straight set and some on point with a medalian center.