Hard shell cases are not really a problem, on the few multiple look alike cases I put a piece of masking tape near the handle and wrote something to ID the guitar with a Sharpie. I now have 5 or 6 Fender gig bags and I'd like to tag them somehow so I don't have to open each one to see which guitar is in the bag. Any suggestions? I went to Staples the other day but didn't see anything I thought would work. Thanks.