EV Builder and friends were in the midst of refitting a vehicle to be of use in a zombie apocalypse when it occurred to them to turn a machete into a variable hex wrench. They liked the result so much that the published the HOWTO on Instructables.
Perhaps one of the more useful tools I have ever owned was a flat bar with a series of hexagonal cutouts in it. While minimally useful as a wrench because of its long length, it proved invaluable as backstop for holding nuts in place while I was tightening them down. Not to mention that when my wrench set was annoyingly missing just the size I needed, my hard to misplace flat bar always had me covered.
It therefore stood to reason that a Katana with a similar series of hexagonal cutouts would be valuable both for taking down Zombies/Mutant wildlife and complementing any set of tools used for post apocalyptic DYI projects. However, after a bit of research it became apparent that in addition to being expensive to make, "Katanas are notoriously high maintenance"* and at ApocalypsEV we hate the idea of high cost high maintenance (www.ApocalypsEV.com).
So seeking a simpler more affordable concept, we created the Mechanics Machete. It combines the Zombie fighting power of a machete with the utility of a set of wrenches. Also when using stainless steel for the blade, it eliminates the maintenance hassle of trying to keep the blade rust free.
Every time I see a hex-wrench made by cutting a shape out of a piece of metal, I remember the time Gatwick airport security stole my belt-buckle, including the little loop that held the belt's tongue, because the loop had a hexagonal cutout that was a "wrench."