Wrist as hinge. Writst and elbow and waist as hinge. Seams, too. All those parts.
Or, one as a whole. But I think knees are fantastic. Depends on the mechanism. I'm still thinking about the mechanism.
Hypnotism is real, though not theatrical. It can be quite healing. I used it on my protags for a long time, and I have become more adept at it. It is an excellent way to get information. It makes them say things. Just as important, though, are physical symptoms; always so ingrained. Nosebleeds and the like. You keep a camera and me (a note taker says he) and you stand by him, to make him stretch when he is distressed. To keep him calm enough to speak and bleed.
I'll write a book then about how I write. I've never met another writer who does it. They probably find it destructive, the points of weakness are most grueling but it's all strength (and bones). And if my protags were female, the entire structure would have to change. It could even change favorably, but I don't care to find out. I write about boys and bones, see.