I am not really sure when you would need a hand-held 90,000 Lumens flash light. The kind of light that lights an entire mountain side from far, far away. It is actually so bright, that I find it hard to think about applications for such light. (100W seems to be enough, no?). But it can be made, so youtuber rctestflight made it, and explained how to build one yourself.
The light is made from 10 individual smaller lights, each made from the following pieces and gives about 9,000 Lumens. The mind blowing total is about 90,000 Lumens.
So each “light bulb” is about $25. Add to that an aluminum bracket, some thermal paste and two 12V LiPO batteries. And you have just made a crazy bright flash light for $300. What will you do with it? I have no idea, it will blind anyone looking at its general direction :), but rctestflight has some ideas:
[1000W LED Flashlight – Worlds Brightest (90,000 Lumens), thanks for the tip Constantin]