Jacob's ladder is a 9 patch, which make it more difficult to try to do as an 8" block. It could be done, but I would go for 9" instead. Then you could calculate each patch as 3". Your 4 patches would be 1 3/4" squares or strips, and your half square triangles would be 3 7/8" or 4" and squared up to 3". A 12" block would have 4 patches that were 2 1/4" squares or strips, and half square triangles 4 7/8" or 5" and squared to 4".