Anatomy of a High Power LED flashlight
(would also be a fitting title here)
I went with components I had because I made this in a haste.
The DC to DC converter is massive Overkill but what you have is usually the cheapest and the yellow lantern body afforded the space easily.
Lithium Ion Batteries and Protection.
Voltage indicator / Battery Gauge
particular construction a lot safer. That said it was thrown together from my UV lithography rig in a hurry. But that's a story for another day.