Summary

The Ball Joint is by DieZopfe - https://www.thingiverse.com/thing:4739696
The Mounting system by HeyVye - https://www.thingiverse.com/thing:2194278

I based the combination of the designs on this - https://www.thingiverse.com/thing:3976976.

I wanted a ball joint for a tablet mount and Fostis' design wasn't quite stong enough to hold it in place so I've used DieZopfe's ball joint. I also added a handle to the screw to make it easier to make adjustments.