I'm looking for a case (or some other sort of protection for my spare 15" MBP battery. I keep the spare inside my Tumi briefcase, which provides all of the needed protection, but since the battery is fairly large, it goes in one of the regular compartments. I would like to make sure that nothing gets in the battery contacts or otherwise damages it. As a result, I'm looking for any case that would fit it well with minimal excess fabric (nylon, neoprene?). Does anyone have ideas? Thanks!