THANKS all, very much! :-)
i haven't forgotten my promise to post a pattern. the reason it's taking so long is that i've been experimenting with different approaches to the method.
depending upon how you size the next round, you can also use it to create diamonds in squares, with seam allowances wide enough to not cut off the points from the previous round.
i'm also playing with approaches that work if you're cutting from fats and yardage and not just scraps.
soon ... very soon. :-)