Hi friend, you project is amazing!
I dont have many expertise in 3d design but i would like to ask an thing to you.
You don´t have the interesting to create a very similar mechanism to laser engraver machines.
Today the big problem with this machines is the adjust of focus, because is very small and imprecise. If we have a method to adjust entire laser module head will help me and another thousand of peoples.
Look how this work today:https://i.imgur.com/036NeF3.png
A simple regular surface to necklace the laser module is enough, i will try to modify your project, but as did say, i'm a newbie :-)
(sorry my poor english)