Buy a Ultratac A1, install a 17mm mtn boost driver and change the led to a XHP50.2 on a cooper MCPCB. Do a spring bypass or install a less resistance spring.
Use a Efest IMR14500 and you’ll be about at 2250 lumens OTF from a AA sized light. :smiley:
And when it’s cold you can use it as a hand warmer. :wink:

Oh, and don’t take walks longer than 20 minutes or you’ll be walking home in the dark. Carry a spare 14500.