If I'm visualizing correctly, you want a finished block that's 8 wide and 12 tall, with 3 fabrics in each, and each fabric patch the same size, with one rectangle horizontal on top and two vertical underneath? You would cut 3 patches 4 1/2 x 8 1/2, so that when sewn together, you have a 8 1/2 x 12 1/2 block before joining with others. I think there'd be several ways to make interesting visual patterns from lots of these blocks, identical in structure but with different (planned or scrappy) fabrics, especially if you staggered them. Well, you'd HAVE to stagger them, because they are rectangles, not squares. -- However, I may have your initial idea all wrong...