I don't know if this will help you but here goes: the 12 sq. pictured is comprised of 4 blocks per row each finished at 3inches..If you want to reproduce the block at 10in. then each of the 4 blocks per row would be 2.5in finished. So. to get a 2.5in finished block you need to start with a 3in..right? Look at the block, looking at each small block that is used to comprise each row. You will see you need to make (2) 3in sq., (8) 3in. 1/2 sq. triangles, and (6) 3in.1/2sq and 1/4 sq. triangles...does that make any sense to anyone but me?