They are nothing but empty hosts at this point as there's no money to spend right now.
The coupling is just an end cut from either the tail cap switch or the light portion as they are both the same length threaded pieces. Not hard to do nice and even being very careful with a 24 tooth count haksaw blade. If you don't take your time, you will end up slipping and scoring the coupling and it certainly won't look as nice.
All you need to make one is 2 of the flashlights which would give you 2 chances to cut the coupling correctly without scoring it. If you bought 3 of them, you would have another rubber gip piece to slide on anywhere you want including over the coupling.
Then you would still have a flashlight you can use too plus 3 AA alkaline batteries. The lights may only be 19 lumens but it is the right amount of light when working close up on things. You can always put it in your car or bathroom or whatever. I've got a flashlight in basically every room of the house and all my vehicles. Never know when it will come in handy.
If you look at the third one in you can see that I had a piece of the blue rubber grip that I cut to size to fit over the coupling.
Give me a sec and I'll take a pic of a couple of the left over pieces (still saving them) that I had cut to show you what I mean.
I also run the coupling over a file to smooth out the cut side better.
I've still got 18 silver light heads from the units I built. Again, this is why you save all the stuff you take apart.
These would certainly work well with a simple module and 14500 (especially with a 5V 532nm from Fasttech using the same general procedure I've outlined with other stuff). The reason why I prefer the 5V ones it they tend to be more likely to put out over 100mw and can more readily/safely handle the ectra voltage of the 10440 although I've never had an issue with the 3V ones. Out of the 2, I would buy the 5V ones as they run the same as the 3V ones with lower voltage.