The age old question- Eye fogging in a mask.

Here is the interior of my Vader Helmet. I outlined the pads to give you a better sense of where there are (since everything is black and blends to gether in the photo) You can see my 3 different squirrel cage fans. Found them on google and the larger one sucking air in throught the mouth grills I found on ebay.

The red arrows show where direct air is blown at all times. The two small ons run off of one 9V batt for both, and the larger is 12 volts so I have a small battery case in there for now with 8 3.5 volt AA batteries.

This in addition to the Rain X/Anti Fog stuff, you can wear this helmet for hours on end for trooping and not have to take it off. Pluss the padding I set up in addition to the entire felt lining I put on the interior makes this helmet quite comfortabel. There are two pads attached to the T-Shaped strap system.

They also sell the anti-fog stuff in spraycans. Check local motorcycle shops.

Another idea:

I have some SCOTT brand snow skiing goggles. Anti-fog, and you can't even get them to fog up even if you huff-n-puff on them. The secret. 2 layers of lens material seperated by a thin wall of air. I don't know how this can be adapted to the Vader/Trooper/Paintball arenas, but it does work well.