Minor modifictions that let it work better for me. Added a 7mm hole in the emitter to allow the insertion of an LED. In the process of building this, managed to break the tabs on the center part, so remixed the tabs thicker. The original lower third of the screwdriver came out about a 1mm wall which seemed to flimsy, so I thickened it up. 2 mm wall. Then needed to print the rings and things that go on it a skotch larger to fit. I kept the original interior dimension in case it was to be used with the original batter pack, in which case that would add additional needed strength. Lastly, since I did not find a readily available source for an original battery pack, I modified a design for a lithium disc hold to take 2 of the CR1632s that I found in my stash of batteries. Good selection, because it is a reasonable capacity and is about the largest disc that would easily fit as a stacked pair inserted sideways.
Modified a great design to hold the batteries and fit the tube. This one:
https://www.thingiverse.com/thing:48606
All that was left is connecting some wires to the battery pack paper clip connectors, adding a momentary switch under the button, and running a single LED into the emitter part. Dobs of hot glue all over to keep it all in place.
Redid the sleeve, cage, and rings at 20.4mm ID to fit the slightly enlarged lower handle part.