It took a lot of gazing and shifting of the circle to finally decide on this:
While the folded fabric looked fine on the right in the audition (here), when I played with a larger circle there was no “right” place. I gave up my original thought, which was to insert something into the squares that did not get the red streak. It occurred to me that there would be other chances to put something there. So I started moving the circle around. It is small plate size–wait a minute while I measure it–I’m back. The diameter is eight inches. I had thought I wanted ten inches, but I don’t think any larger would have worked.
And I must say, it is the best job of inserting a circle that I have done yet. I use the Ricky Tims no-pins method. On my other tries I’ve ended up with small tucks or pleats. The last time I tried I didn’t trim the seam allowance down to the scant quarter inch, so then the concave couldn’t stretch enough to fit the convex. And the first time I tried a smaller circle than recommended. On all previous times I’d been rather careless about the angle of my registration marks so that matching them wasn’t exact. This time I was careful to make them perpendicular to the circle line. Both details helped a lot.
Clue three has been give–click if you want details. I am pretty sure where I want to put the two “neutral” rectangles; I am totally clueless where I might put three triangles. I have two weeks to ponder.
Oh, and I cheated a bit. Directions were to stitch all squares. I stitched only the ones that needed to be together to add the circle. It is easier to work with small pieces. We have photographic evidence of my plan, so I’ll not be able to cheat and rearrange any squares.