I wanted to be able to pose my PVC mannequin and didnt love the options out there. Ball joints didnt give enough range of motion.

Embed an M4 nut into the "to Shoulder". At 0.2mm layer height and no raft it should be layer 26 for the pause
Connect Mid and to Shoulder parts with an M4 screw (with thread lock if you wish)
Use any bolt/rod you wish through the hole in Mid and Arm
Each end is designed to slip inside 1" PVC pipe