I have been hunting for a slick AAA LED flashlight for years, and recently found one directly from China. It looks like E12, by the way, but proportionally scaled down (and like 10 times cheaper).

http://www.ebay.com/itm/161347164023?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

And that's exactly where I saw obviously non-concentric drilling (just for .5mm approximately, but clearly visible, I'll make a photo when I'll get home today).

The size matters, I'm EDCing my 0.5" Solitaire with LED drop-in upgrade for like 7 years already in the Leatherman Wave holster's side "pocket". And that's a tight and smooth fit already, which I like a lot. Its thin aluminum walls are well worn, but in perfectly functional shape so far:






I would prefer AA as well, however, they are even more overbuilt and often irregularly shaped (E12 is 0.75" vs 0.57" for fattest AA).