From what I see, I guess you went the route of two detent balls (one for open and one for closed position). Somehow like Kansei Matsuno does (Böker Wasabi). It's a cross of friction folder and flipper. And it's definitely interesting while I just miss a positive lock to closing. You could do away with lots of precision machining, ditch the detent balls and replace the flipping nub with a lever. Et voilà ! A friction folder ! The bolted pivot would make for very accurate tuning of opening and closing action, a long enough lever would give absolute control over the opened blade (only precision work is the placement of the stop pin) and... the price goes down a little more. I love this classic blade / handle pattern and I will be all over it once you make some of them available, whatever route you take !