I'm going to build my own battery.
Using Panasonic NCR18650B's
Found this test tube holder
https://www.indigo.com/lab_supplies/test_tube_racks/33770-plastic-test-tube-rack.html#.Vldox19OLKD
18mm holes. Want to use 8, 4 as is but inverted onto the batteries, and 4 cut down to fit and be epoxied...