Most of today's crop is the usual scrap-metal clickbait — "genius" tools shot in heavy slow-mo with no explanation of why any of it works. This one from UnlearnedThings stands out because it tackles a problem every shop eventually faces: dull twist drills pile up faster than you'd think, and a decent commercial sharpening jig runs well over a hundred dollars.

Building your own forces you to understand the geometry that makes a drill bit actually cut: the 118° point angle (or 135° for harder metals), the relief angle behind the cutting lip, and the importance of keeping both flutes symmetrical so the bit drills on-center instead of wandering or oversizing the hole. A homemade jig has to hold the bit at the correct rotation and feed angle against a grinding wheel — solving that mechanically is a great lesson in fixturing.

At 124 subscribers this is a genuine small-channel build, and the description suggests the maker walks through the principles rather than just montaging the assembly. Even if your version ends up rougher than a Drill Doctor, you'll come away knowing what a properly sharpened bit looks like under a loupe — which is honestly the more useful skill.