Parts were collected, and bodged together. I did this all the week before going camping for a week - I figured that would be a good test.

Initial math told me with a 3.7Wh cell I should get 48hr runtime if I use less than 20mA, so I used a 220ohm resistor. This gives ~17ma at 3.7V nominal for the cell.

I whipped up a quick 3d printed clamshell prototype, charged it up, and went on vacation.