odd question about the key fob

I just purchased a 2010 Prius II yesterday and the one issue that I have is regarding my hobby. I play regional paintball tournaments and practice every week. With my old car I would wear a lanyard around my neck under my jersey with the a spare key for the car.

Since the Prius uses a fob I worry that carrying the fob with me could damage it (sweat, getting shot or crushed). I was wondering if there is a safe to leave the fob in the car and just bring the door key with me instead. I was thinking of some sort of box/bag that I could put the fob into that would make the Pruis unable to see/read it. I know thinkgeek.com has wallets that block RFIDs so I was think something similar.

The only down side is that if the car was broken into they could find the fob and be able to drive the car, but since they could have just hot wired my old car its not that big of a change in threat level to me.

If anyone has any better method or idea I would great appreciate the input. Thanks.

 

awesome, thanks