I like to have a reliable way of lighting a fire on me at all times. The most durable firelighting system is a ferrocerium rod, but these tend to be a bit large and don't hide well from Australian airport insecurity staff. So I invented my micro-tinderbox, that is extremely lightweight, works after a thorough soaking and drying, and strikes on a TSA-approved blunt nailfile or the file on your multi-tool.
To catch the spark, make a wad of charcloth, which you hold next to the flint when striking. Put the whole lot in a little baggie - with a spare flint - and hide it away for a firelighting emergency. Ⓥ