I have the exact same problem with mini/micro kits. I start packing them and before I know it have a full size tin kit or even a belt pouch-sized kit. I'm working on a micro kit right now and having lots of trouble. I'm trying to come up with the most functional urban/rural 72 hour kit I can in a container about half the size of an altoids tin. So far I'm not having much luck. Once I at least get a decent start on it I may post info to try to get help from the group if I'm still struggling with it.
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Learn to improvise everything.