After seeing Adrians light sabre last night i am thinking of making one.
I already have one of these handy USB
powerbanks from Kogan (5v, up to 2A output, 6600mah).
I am thinking of buying a 50mw 3-5v laser module like
this and terminating the wires into a USB plug, so it can be a modular attachment to the powerbank. The on and off button is on the powerbank itself
Ive already made a USB fan from an old cpu cooler and it works just fine with the powerbank.