I was inspired by Sebastian M. and his holder HSW Batteriehalter AA & AAA - https://www.printables.com/cs/model/675021-hsw-batteriehalter-aa-aaa
So I made my own model for 18650 Li-ion batteries, with some upgrades.
My version for 18650 batteries is printable without support in one piece, but I had one support under bridge. This is printable without this support. First piece was printed with 3 perimeters and 10% cubic adaptive infill and it works. Be carefully with speed and cooling. My was made with 0,2 mm layer high and looks great. You will be needed three (maybe two will be enough) M3 inserts for HSW system - https://www.printables.com/cs/model/152592-honeycomb-storage-wall/files (added to my files).
Enjoy
The author marked this model as their own original creation.