tripod - 4 degrees of freedom fixed with one screw

#tested with OpenSCAD 2021.1#

there is a bunch of tripods in this forum, but no one with the ball design I had in mind. So I created it. The central mount pipe has 4 DOF all fixed by operating one screw as shown in my [little demonstration film](https://youtu.be/azHI0TdrvGs).

The screw squeezes the socket, and the socket the two ball halfs.

The design is optimized for printing. I printed mine for use with 10mm aluminium pipes (using 0.5 as scale factor) and with threading. It came