Interesting about the pivot, as it looked to me like two balls and I couldn't see how it worked. For such things, you generally want hard steel against hard steel at least (steel balls from ball bearings are usually a 52100 steel, a rather ferociously tough steel). Even better is hardened steel against an even harder thing like sapphire, etc. (e.g., remember the "jeweled bearings" of watches?).
Here's something that appeared in my brain immediately upon looking at the design (see attached picture).
Part A is made from drill rod (in the US, either O-1 or W-1 (e.g.) hardenable steels). You machine it soft then harden it with a propane torch and an oil or water quench. The nice thing is that it's simple to make on a lathe -- turn down one end for inserting into the long arm and securing with a set screw. Then the other end is center-drilled. Harden it. Then you can make a simple brass lap and lap the center drilled hole's face to a nice polish. This is the hardened surface that bears against the ball bearing. The ball bearing could be held with wax or somesuch in a hole in the support (I'd use a ball end mill because I have some, but a center drill would work fine here too).
Even without a lathe, it wouldn't be too hard to make such a thing with files and a drill press -- or even a portable electric drill. The turned-down section could instead be made by Loctiting a pin into a drilled hole (or use a spring pin -- virtually no work).
I'd make a first one without bothering with the lapping. Total time to make the steel piece would be less than 10 minutes with most of the time for heat treating. Stop by the house and I'll make you one...