Originally Posted by Chele

I think if you use 9-1/4" squares, they'll cut down to 6-1/2" and when you put the four together into a pinwheel, they should make a 12-1/2" block. Use some scraps and try it out first. I was using my proportional scale to figure it out.

I have got to try this method for half square triangles. Genius! Show us what you make!