That's the link to a video Chris Fawcett made showing how it's done. He demos with two different dovetail plates (and I've seen it demo'd via FaceTime on a third plate I did not recognize - action cam? it was red).
Regardless, it should work for $0 for some operators (Archer2 owners for sure) and for only a few bucks at most for everyone else (you may need to get the small threaded washer from Tiffen or make one up or maybe use a thin nut).
BTW, Chris is off this forum for awhile, or he would have posted this himself.