I have an insulated copper strip running down inside the battery tube, one switch terminal connected to it in the tail and the other connected to the flashlight body. I didn’t have the right materials to make a tube yet.
If you look at the driver pic you will see an additional brass ring sitting on top of it, this has the e.switch wire soldered to it and is insulated from everything else and epoxied in place.
The copper strip (you can see the end of it just poking out) running from the tail connects with this when the head is screwed on.
Here’s a Novatac 18350 mod with the same principle.
