I should take a picture of it, but that collar was surprisingly easy (if not time-consuming to do). All I did was take a piece of foam rubber about an inch tall x however long the neck has to to be and folded a piece of felt over it (if I had Spandex, it would have been easier).
I then sewed a straight stitch on the machine every half-inch trough both layers of fabric and the foam, creating the ribbed effect. Once that was done, I ran a stitch all the way across the bottom and attached it to the maroon shirt part.
You might be able to modify this technique for use on your films, if you want. I would just leave the back open put a snap in to close it at the back so it could go over the actor's head.