I picked up one of the bags with slots designed to carry USB cards and it's perfect. I got it at Office Max for $7. I can fit about 8 3ml bottles of liquid on one side and batteries, atty's and carts on the other. Well worth the $7. I think they carry them at Office Depot too. They are sold online for even less, but I wanted one NOW so I paid a few dollars more for my lack of patience. 
