Here is the collar, still not turned right side out:
I have folded it in the middle so you can see both ends and the contrasting sides. I have also interfaced both sides of it.
After I attached the sleeves to the shoulders (I will sew up the underarm seam all at once), I hung up the coat to have a look at it. The stripes are maybe a little - mattressy, pyjama-like perhaps? Maybe they should have been bolder? I was thinking that I would alternate every time I wore the coat so it would get even wear but now I am wondering if I will prefer the red side out with the striped side as the accent. Just musings at this point - when I get the whole thing put together, I think I'll have a better idea.
After I took the photo of the coat as it was hanging up, I folded over the shoulder seam allowances to finish them in the usual flat fell. You can see in this photo that the front piece is interfaced and I have finished the shoulder seam in a modified flat fell. Now I just have the underarm seams left, which I will finish in a modified flat fell. Once that is done, I will put the red side of the coat together to the same stage the striped side is.