I’m not sure how accurate this is, and the pacing in a little slow, but this guy has made some interesting friction folders based on whatever research he may have done, and one looks very much like the Piedmontese mentioned above:
I would be interested to hear what Jack has to say about his information concerning the penny knife manufacturing. It seems to be in line with what I have heard here about the way things were set up in Sheffield and Thiers, with small workshops providing various parts which were later assembled into the finished product.