Several years ago modding maglite solitaires was popular, but most mods used unconventional batteries and direct driving pathetic little 5mm LEDs for a couple of minutes runtime. I think one person did manage to make something half decent with a luxeon but it had crap runtime. In recent years torches like the ITP A3 and Fenix E01 have appeared, now people don't bother with solitaires as they can get something brighter, cheaper and better quality ready to go out of the box. But the technology is available to make a good solitaire, if you cut open one of those led drop ins for mag 2D's you'll find a boost circuit that will fit inside the maglite solitaire, the circuit seems pretty good, I've only tested it with an old luxeon but the output from a single AAA around 10 lumens, with a real LED such as a Cree XP-E it could be 20+. This mod is on the waiting list but not a priority so I might get round to it one day.