<tired> Got my 3D-printed parts today and assembled my two On Beam clutches...I think they will work. The spring is a real pain if it has been unsprung like mine was. I got it rewound close enough that the clutch works. The other spring was fine, so now I have 2 working clutches!
The spring has to be just right for the clutch action to work. I spent all day messing with the things, and really got my hands sore...friggin' arthritis is a bitch.
The 3D-printed parts did need a little razorblade scraping to fit, but overall they were damn close. They look like they will be plenty strong for the application.
I used FreeCAD to model the parts, and sent .STL files to JawsTec in Idaho for printing. Only beef I have is how long it takes to get the parts. You can get materials and processes that aren't generally available for home 3D printing. I used MJF (Multi Jet Fusion) Nylon for these. They also have ABS, which I'm trying on some other parts, and other materials including sintered metals. Pretty awesome technology. I used to use 3D printed parts in my engineering days in the 90s, but they were not useable as "real" parts, only as models...the material was too fragile.
(black parts are the new 3D-printed outer cams)