I realized that the challenge ends Sept 1st and I need to get moving!
I decided to stitch the rim on the large wheel using raised stem stitch. I had stitched on some batting to pad it, but realized that was a mistake--it was too easy to catch in the needle. For raised stem stitch you don't go through the fabric, but skim the surface to make the stitch.
Above is my first bar--most of this will be off the edge of the picture, so I'm going to leave it as is, even though I'm not thrilled. I did learn a lot about doing the stitch.
For the second band, in the upper left, I removed the batting and stitched over a piece of paper. That worked much better. For the long band on the right, I left the batting but added a piece of paper on top of it so I have the padding but could also stitch without catching it. That worked very well.
I've also added a circle in the center--part of the next layer of these articulated arms that come out of the center.
I cropped this picture (above) to the edge, just to see how it looks at this point.
And here's a hint of my plans for the next step. I'm covering wooden coffee stirrers with fabric to make the articulated arms. I've decided that I need to give the piece a good pressing before adding these more dimensional elements and I haven't been home yet this week to do that.