DIY all round LED kayak light using 18650 batteries

Filmed vertically because, well, it's a vertical item :)
The light is available at www.amazon.com... - there are other suppliers, however this one has US based stock that was faster to receive. It is cheaper elsewhere, but be aware that some suppliers use much cheaper LED emitters that just look downright hokey.
Light and mast parts list, from the top down:
• All round LED light - nominal 12V, works from 10V to 24V. Includes an 1157 LED emitter, 2.5W.
• 1-1/4" slip coupling as light holder - need to dremel it out slightly for the light base to fit inside
• 1-1/4" x 3/4" reducer bushing
• 3/4" x 48" Schedule 40 mast (not pictured)
• 3/4" x 3/4" x 1/2" tee for switch
• 12V switch, as inspired by Fishin N Stuff's light video • Kayak Nav Light DIY (U...
• 3/4" x 3/4" x 1/2" tee for wire exit
• 1/2" x 1/2" street elbow for wire exit
• 1/2" plug for wire exit - I drilled two 7/64 holes for AWG 14 wire to pass through, and sealed it with Goop
• 3/4" x 10" Schedule 40 lower mast (not pictured)
• 1/2" slip plug to seal lower 3/4" Sched 40 mast - heavily dremeled to fit
Optional base inside the milk crate - there are other options for mounting PVC. It does slide out, just needed two hands!
• 1-1/2" x 3/4" reducer bushing - inside lip dremeled out to allow 3/4" lower mast slide through
• 1-1/2" slip coupling
• 1-1/2" x 6.5" Schedule 40 PVC
• 1-1/2" slip coupling
• 1-1/2" x 3/4" reducer bushing heavily dremeled to be inserted in reverse at the very bottom of base
The battery pack is 18650 lithium ion - the prototype pack shown in the video is a 3S 12.6V pack just for testing purposes, the proper pack will be a 4S2P 16.8V pack with BMS for battery management. DO NOT build an unprotected battery pack like the one shown in the video unless you are very familiar with Li-Ion batteries - at best the cells are easily damaged by overdischarging the pack, at worst you can have a fire while charging. Plenty of house and car fires caused by Li-Ion charging.
USCG lighting requirements for "vessels under oar" can be read at www.navcen.usc... - an all round white light isn't actually a requirement for kayaks, but having a white light of some type on hand is.