I wasn't going to make bound buttonholes, but when I got my buttons they were too lovely, and I felt they deserved bound buttonholes. So I made them the same way as the buttonholes on my green coat, which was to make them using the instructions from this ebook by Karen from Did You Make That?.
This method uses welts to make the "legs" of the buttonholes, and I found this to be so much easier than using the method with a patch of fabric. Here's what my buttonholes look like. Sorry about the fuzzy photo!
And here's what they're like from the back.
This is my practice buttonhole. Needless to say, I'm pretty pleased with them!
The back stay helps to stop the upper back of the coat from stretching. I drafted mine using the Craftsy Class "Classic Tailoring: The Blazer". These attach to the centre back, side back, and side front pieces.
Here are the pieces attached to the back of my coat. They are sewn to each piece within the seam allowance, then the coat pieces sewn together. The bottom edge is cut with pinking shears so a ridge doesn't show through.
I've also seen back stays made in one piece, and did this on my green coat, but it makes more sense to me to support each seem.
Next time I shall waffle about the interfacing.