One thing I would not want to do without in a bug in or bug out is a pop rivet tool and an assortment of rivets. they can be used for repairing packs, sheaths, sheetmetal and lots of other stuff, and for making new things, too. They are small and relatively light weight, especially compared to their usefulness.
Just my thoughts.
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"Most men take the straight and narrow. A few take the road less traveled. I chose to cut through the woods." ~Unknown~