9 Volts

First there was the pak-lite, a commercialy made torch that you clip onto a 9v battery [History: some kid made this when he was 15, now he's 20 and living it up]. Then some smart arse came up with the diy version, which uses an old 9v battery connector to put led's in and hey presto, 9v battery torch [History: the same guy that made the tictac torch]. Then some other design folk, took this idea further and turned the torch into a kind of mini lamp/candle [History: insponse to those rechargable candles]. Now there is an instructable on how to make a solderless 9v lamp.