A big part of survival is making the most of what you have, and often this means re-purposing trash into treasure. Whether it's a tin can stove or a fertilizer compost pile, it's wise to learn how to make what you need rather than relying on local stores that may be picked clean in an emergency situation. That's why we enjoy seeing scrap materials turned into tools and weapons — for example, a PVC pipe bow or a file utility knife.
We recently came across a video from YouTuber AverageIowaGuy that shows how to make a parang knife from a lawnmower blade. It's a relatively quick process to form this traditional chopper, and only requires a simple homemade propane forge, peanut oil for quenching, an anvil, and a few other tools found in most garages or workshops. That may sound like a lot to someone who's never made a knife before, but in the modern knifemaking world of million-dollar CNC machines, it's positively primitive.
Check out the video below. One thing to keep in mind is that steel quality can vary greatly among lawnmower blades, so you may need to sharpen the edge more often if you end up with a softer donor steel. You may also want to consider other steel sources, such as truck leaf springs, a material commonly used for knife-making in southeast Asia due to its relatively consistent strength and flexibility. Regardless, do your best with what you've got — a knife that dulls quickly is still far better than no knife at all.