This is the Wireframe of the Head.
It is made of 4mm aluminium-rods wired together with metal wire and fixed with hotglue.
The Joint is made of pieces of Circuit-Board and spacers.
It may sound odd, but Circuit-board (Epoxy, not pertinax) is a fine and sturdy material and the spacers keep the parts apart and simultanously work as the axle of the joint. (Um, I really hope anybody understands me)
Click on the pictures for a larger version.