The project has 3 components, each requring a PCB and 3D printed housing:
Battery Canister:  a PVC pipe body will house an RC type LiPo battery (4S) and custom BMS.  A 3D printed cap will allow 2 or 3 orings to seal the top of the PVC body (bottom will have a glued cap).
Flashlight: a 3D printed housing will contain a high power CREE LED with a magneticly operated (via reed switches) binary counter to control the output of the LED driver (constant current).
Charger: a USB-C PD PPS controller will negotiate the proper CC/CV conditions from a standard charger to recharge.  This part wont be waterproof.