On that subject, I just use brown B-50 and brown serving string.
I was wondering though, do you all dry twist your sinew strings. I wet twisted the one I made, and it didn't look nearly as white and fluffy as the one in the pictures when it was dry. It was about a quarter inch thick when it was wet, and dried to 1/8. I dried it with the loop over a dowel, and a weight clamped to the other end. When dry, it was hard and yellow, then I sanded the rough fuzz off of it.