The survivor/prepper movement is rife with good ideas for homemade (of necessity) tools of various sorts. In the extreme situations posed by their premise, there's always a need for fire starting tools, first aid kits, water purification techniques, etc. If you haven't previously encountered their perspective, it's worth considering and at least a bit of investigation. Start here with these videos:

The Ultimate Pocket Survival Kit by SuperEnginerd

Micro Emergency Fire Starting Kit Tutorial by MeZillch

Biosand water filter DIY homemade survival water filter by desertsun02

Ultimate homemade survival kit by ArmyRanger10a

Homemade Survival Kit by thesurvivorguy3