I know I am missing something but I can't see how this works. I have a copper nova heat sink that screws into an aluminum 'shroud' that holds the lenses for the LED's. What I can't figure out is how this mounts inside the tube and what holds it.

I'm making a custom hilt on my lathe. I will also make a custom blade holder/emitter. I know the heat sink/LED's go between them but how? What am I missing?