Well, Ed, I am still waiting for my order to John to be filled at this point. I placed the order for three plugs (two for J Frames and one for K Frame) in mid January. John has communicated with me a couple times in the interim and indicated he intended to complete his standing orders but would not likely be taking more orders, at least not anytime soon. I haven't bugged him about these because of the health related situation he faces. I've been thinking about trying to contact him again and see if he would prefer to just cancel the order and refund my payment to him. My feeling is that if he were able to complete my order, he would do so. I'm not complaining here ... stuff happens, and I believe what has happened to John is certainly pretty much beyond his control. I think he fully intended to complete my order and has just not been able to do so. I do not know what his chances are for recovery to be able to do so. At this point, I have my doubts, and for that, I am sorry! I would guess he might respond to an email from you and shed some light on that situation. He has been willing to do so with my inquiries.
I'd say if you are willing to take on this task, there would be some interest, based on comments and questions here on the forum, but I can't say if the level of interest would be worth your time and effort to get them into production. I'd say being able to produce the plugs for all three frame sizes eventually would increase the number of orders.
I've considered restoring the external plug with the spring and yoke that holds it in place internally and leaving out the flag portion that causes the problem. I can't really see any reason why those parts would not stay in place, but since the only gun I've removed the lock on is my EDC, I've been hesitant to take a chance on that. I can live with the hole, and as things are now, there is nothing in place to come loose and cause a problem when I least need one.
So, I would tell you that I definitely would be interested, especially for the M642 J Frame I speak of. I'm glad to hear that you are considering this project. Based on my experience with your sight pusher, I have no doubt you'd do a great job of producing these items. Since I have not received my plugs from John, I don't know exactly what his product contains as far as parts are concerned. If it's just the plug, which uses the existing internal parts to hold it in place, then my concern would evidently be unfounded if I were to put my existing lock plug back in place minus the flag.
I hope things work out for John, whether or not he is able to ever continue manufacturing his plugs. I also hope you can decide whether or not you can start production of these without crowding his business. I appreciate your concern for that. Good luck!!