Project COOOL DUUUDE

[bigsharn]

Ok, well as a few of you know I overheat easily, especially when out on bike rides, so I was after a way of cooling myself down without forking out a fortune on cool suits etc.

Roll on: Project COOOL DUUUDE

Basically, the plan is to find a way to keep me cooler at work (and less so on bike rides), knowing that I have a few no-name case fans around I was thinking of mounting one in the hat of my uniform so that when I take it off, it won't be caked in sweat... As such I'll need (at least):
A pressure switch
A PP3 battery and connector
A fan capable of moving lots of air, very quickly (though testing will be done with a no-name fan so I don't blow it up)
A fan guard (so as not to give myself a haircut every time I turn it on)

...I say "at least" because I'm highly tempted to wire two batteries up at once to the same fan, I don't know what overvolting a fan will do other than make it go faster, but I also want the setup to be waterproof, so I'll need to come up with an enclosure for the entire thing (probably butchering some plastic mack and a lightweight material for the frame).

Any thoughts? Especially on overvolting the fan?