I doubt if this will ever be duplicated. (UPDATE: I stand corrected) But just in case, here you go. I got married recently, and one of my geek duties for the wedding was to light 75 paper lanterns in the reception tent.
Commercially available solutions advertise a 12 hour life, which is much too short. So I designed something that uses 2 AA batteries to power 3 LEDs.
...it may have been overkill. It's been almost 4 weeks and these things are still going.
for more detailed information on motivation / construction check out: http://brettbeauregard.com/blog/2011/08/when-a-maker-gets-married/