Ball & Socket & Elastic Joint

Hi all.
Today I thought of a simple way of holding a puppet head in a body, while making it removable at all times (interchangeable heads on this project).

With my colleague Daniel, we ended up with a very strong and tight ball and socket movement.

The system is very simple. A spherical hole in the wooden body, for the ball joint of the neck, which could be metal, wood, or plastic. We had a metal ball bearing that had been tapped to add threads inside, to fit the bolt that makes the neck). Two holes are drilled very close together, on both sides (left and right) of the center of the neck. The holes are drilled from outside (tarting at an angle, away from the shoulder articulations) and reach within the neck hole.
Elastic cords are run through each set of holes, making two straight lines crossing the neck opening. They are tided outside with knots, tightly.
Now here's the only tricky part (not a challenge at all): how to insert the neck ball in there.
All you need is two straight stiff rods of some sort. I use big nails or whatever piece of straight rod that's lying around. Lift one elastic out of the hole with one rod, and hold in place. Do the same with the other elastic. Slide the ball in there, release the elastics.

The hold is very strong, it won't let go until you want it to. Tension on the ball bearing from the elastics pushing it on the wood makes a very tight joint, without any parasitic movements.
Pull very hard to release the head again. We added a metal ring, made from a pipe we cut, to re-enforce the neck, but I don't think it's really necessary (but it looks neat!).

I love this system so much, I can't wait to make another puppet for myself and give it this neck system!