I designed these components for a Smartphone holder (http://www.thingiverse.com/thing:1778271). I thought that other people might find the ball and socket assembly to be useful for one of their projects.
Unfortunately, I resized it a few times to fit my project. I wasn't planning on sharing these parts at the time, so the thread dimensions are no longer a standard size but hopefully that won't matter for your project.
I have uploaded a couple of renders to show how the threaded nut should be assembled.
If you use this, please mark it as a remix. I'd love to see what people do with it! Thanks!