I keep going back to the BLF Sabre design because that is exactly what it was designed to do. Separate the head and cool it from underneath.

Instead of re-inventing the wheel, I simply stole the cooling design of CPUs, which is pretty much a “mature” method of cooling and applied it to flashlights.

Fans are dirt cheap and take very little draw. Even passively, the extra cooling right behind the LEDs helps a lot.