Ball Head Links System - Barrel 20mm (Evolution 2)

Chain links to be used as bracelets, chains, belts, etc. The outer shape is a barrel type shape (radius 10mm), but it can be easily altered, as long as the male and female connectors stay the same.
I tried to create a shape that is more prone to be 3d printed without supports because it turns out the first generation links tend to have a weak male connector, depending on the filament used.
CAREFUL: This is the 2nd evolution step of my Ball Heads Links System, the connectors do not match the original links to be found here: http://www.thingiverse.com/de_baseggio/collections/ball-head-links-system.