I was looking for a very little vise for the small woodcarving knives I'm starting to make (just posted a thread showing my first attempts). I didn't like most that I saw, and some of the bigger vises are just out of my price range just now. Then it occurred to me that I'd seen some photography tripod heads which had nice smooth ball/clamps, and some of them can take quite a bit of weight. I'd have liked to have the clamp thingy sticking straight up from the socket, so I could leave it in and rotate it to get at the bottom of my blade, so I might JB Weld a connecter nut on it. I also thought that I probably shouldn't have drilled through both plates in the middle wing nut – should have drilled through the bottom plate, and threaded it to have an adjustable-thickness thumb screw. This one seems to have an aluminum alloy ball-and-threads, so it won't take much abuse, but if it works I may buy a bigger, less cheap socket head. I plan on mounting it to a board, with some sort of safety bar/post in front to stop me from stabbing myself (again). I was going to post this on Rob Watson's thread, but seemed like hijacking it, and this isn't really in the same caliber as his really nice one.
That's a very cool idea. Let us know how it works out. I wouldn't mind doing something like that for holding small folder parts for sanding. My knife vise is sometimes too much for a small back spring or butt piece.