Thanks, Riversong! I decided to try making one using a stray block that had no purpose in life. I had a bit of a struggle with it because I wanted to quilt it after birthing it. That was probably asking for trouble. I made the darts in each part separately. If anyone else is considering this, I'd say it's not impossible, but even with the free-arm it was tricky keeping things lined up, and I had to do a little unstitching to remove a major pucker. I'm not ready to throw it out, but it would have been a lot better to quilt just the top and batting, while flat, as the directions say. This one started out with 12 1/2" squares to accommodate the size of the block, and I also used a circle that was about an inch bigger than a CD. I used a glue stick to hold it in place before making my sandwich.
Another thing worth mentioning is that if you want to use a pieced block, keep in mind that you are going to be taking the darts out of the sides, and not all blocks will look right with that alteration. This sawtooth star block had a fairly large plain area on the sides where the darts went, and with the sashing around it, it fit with most of the dart in the sashing.