New submitter SkinnyFatSmoothNeck writes "I'll be taking a long train ride in the coming month and I'm looking for ideas and recommendations on anti-theft devices to be used for carry-on luggage. The obvious precautions are always taken: never letting the bag out my sight, wrapping the bag strap around my leg while stowed and so on. But as this is a long ride, there will be a couple of nights involved. The first thing that came to my mind is a two-part device that triggers based on a specified proximity and is controlled from a remote (ie.: the device would be placed inside the bag and trigger a loud alarm if it strays outside of range). Perhaps a more advanced, albeit more expensive, device could also include GPS tracking. But beyond that, what other creative, ingenious or downright sensible solutions do you have to offer?"