18650 cell carrier for Meshcore "discreet" node

I'm getting into Meshcore.
As part of this I've seen few "discreet" repeater designs which are generally put together from various solar lights and other bits and pieces.
I have used PVC tube in the past for similar outdoor projects and found it to be very reliable and easy to make weather/waterproof.
I wanted to experiment with a method I used previously and needed to be able to secure varying numbers of 18650 cells in a small carrier that fits into the PVC tubing.
The battery carrier also holds a small charge board as shown in the images which allows rapid charging at 1A/hr if needed.
The carriers have a central hole/shaft which I used to run the main wires to the batteries (which are wired in parallel) from the charge board. The charge board can also be wired to a 5v (6v MAX input) solar panel to charge the batteries.

There are currently 2 versions of the carrier:
38mm which holds 2*18650 Li-Ion cells -for a 40mm I.D. PVC tube
49mm which holds 4*18650 Li-Ion cells -for a 50mm