I am a complete novice at making any kind of feather, but here is the method I used to create the curved feathers in my Retro Flowers Quilt petals. I don't have a long-arm . . . just my trusty Bernina, a darning foot, and lowered feed dogs.
I created a template for the spine of each feather. I hate to mark, so I just lay it on the quilt and use it as a guide to stitch around. I use this method frequently (see the stars on the Independence Day Quilt and the large petals on the Heirloom Quilt). The template gets pretty beat up, but I think it beats marking any day.
You'll notice a mark on the template. That's where I stopped, removed the template and then stitched on the same line back to the beginning. I've since learned that it looks nice to create an increasing gap as you return to the beginning . . . just like on a real feather's spine.
I began on the outside of the curve, creating the "bubble" on the outside of the feather. Another thing I wish I had done: curved the spine in a little bit at the beginning (creating more of an "s" shaped spine) so there was a little more room for that first bubble. I got into a rhythm, creating the outside bubbles all around the outside curve.
When I reached the end of the spine, I made sure the last bubble blended into the end of the spine. At that point, I started to create the bubbles on the inside curve.
The picture below doesn't show it very well, but the inside bubbles on that tight inner curve were really long. The inside curve of the bubble creates the shape of the next bubble . . . almost like a yin yang sign.
Continue on the inside curve until you reach the end. At this point, I just stitched a few stitches to the next petal and only cut threads when I had finished all four petals
My mantra is to learn something new on each quilt I make. This was a new challenge and I certainly learned some things that would make it look better next time. Don't be afraid to try. After all, crappy quilting won't stop it from being a cozy blanket, right?