Initially I had planned to make sixteen blocks (they finish at 6") and put wide white borders on them, then apply a 9" template to cut wonky blocks. Turned out to be a bad idea -- they really wanted a 12" template and that just was going to use up more fabric than I wanted to spend on this project.
Himself is partial to tiny cornerstones under almost any circumstances, and I thought they might work very well with these blocks. So I made nine more and went with that plan. We're both pleased with the outcome. He says they look like signal flags. He's right.