I did this a long time ago but some how I did it wrong and the batteries got hot, so when I took it apart I never reinstalled it.
what you will need
- computer mini fans
- 9v battery cable
- soldering gun
- zip ties
- on/off switch
put all the red wires together
putting in the zip ties
everything worked, I thought I was done...
before you put the fans on make sure they don't poke you in the head, had to grind it some.
the battery is just held by the head strap, it works fine for me.
I do not recommend the one made for the mask, it's in the black one. it's not work the money.