And then marking the grid on a quilt sandwich and stitching/practicing. At the top I did rows of the spirals in both directions, and then rows of the reversing spirals, and ended with a row in which the exit line is right on top of the spiral in (a new look)
And here's what it looks like after the washable pen is washed off (OK, it's upside down) (and the back of the sample is at the top of this post).
Top thread is Superior's Rainbows, a 40 wt. trilobal polyester (my first use of poly thread!) in color #801 "Jester", and the bobbin thread is Superior's Sew Fine, a 50/3 polyester, in color #450 "Spring Green". Used a 90/14 topstitch needle on quilting cotton with 80/20 cotton/poly batting and had no tension adjustment issues at all.
I still need a lot more practice making smooth curves, and spacing lines evenly, but even all irregular as it is, the pattern has a certain spunk and movement that I find charming.
Everybody's a critic.