light head designs

[Goldigger]

I bought myself a mini mill a few months back and have been busy making bicycle lights..

Here's one I made earlier

As I have the mb sub, I've not been to fused about making a dive light, but its still in the back of my mind.

So I'm curious as to what is achievable on my mill, the only thing that I can't do on the mill is threading..

How would you guys make the head water tight? Face plate screwed down compressing an oring?