I've seen these before once, but have no idea how many are out there...but I would love a Nekomane tailcap (to enable tailstanding) for the U2! If you have one, give a a holler :naughty:
I use a leef tailcap to stand mine, though I had to remove my pocket clip for it to screw down far enough... Lighthound sells them. Add a leef U2 body and you'll be able to use 18650 rechargeabls in it... gives looooooooong runtimes.