First I cut the dark purple center for the back as a square instead of a rectangle. Then I sandwiched the quilt without realizing that the light purple border on the back (because of the first flaw) would be completely off the edge on one side and a little too short on the two adjacent edges. Then I quilted one border side STILL not realizing the mistake I''d made. It was quilted on the short arm and when I hauled it off the machine to look at it I realized it looked like POOP so it got shoved to the side until Terpsichore arrived. A few weeks ago I pulled out all the quilting stitches that were already in it, then I de-sandwiched and re-sandwiched it and took it up to the longarm. Turns out the back was configured wrong. Huh. Go figure. After extensive retrofitting of the back, I put it back on the longarm and ended up unsandwiching it again and just rolling it onto the machine like you're supposed to. Oh, then I figured out that one edge of the batting was about four inches too narrow. I added an extra strip.
I flip flopped for maybe a week between green thread and purple thread and ended up with purple because it matches the back. The wonky feather pattern worked out well, and it took maybe three hours to quilt the entire thing including the fancy border (hourglasses with waves inside) in a different color.
It still felt like I was bringing down a horse. But it does bring my total to 16 of the 22 original sandwiches finished!