EASILY CREATE BALL SOCKETS BY FINE TUNING THE SETTINGS IN THE ADDON PANEL 

Once you have your desired settings in place all you have to do is  click the "ADD BALL SOCKET" Button and it will generate 

You may also create all kinds of joints, such as hinge joints, with their own sliders!  The hinge also comes with a center pin ready to go!

This addon makes it so much easier to get the sockets fitting nicely instead of testing alternatives and wasting material; these are guaranteed to fit