Probably nothing - It seems mostly that people who cut gears in metal would not use paper templates. In wood, I've cut gears with my CNC Router, that works gre

Probably nothing - It seems mostly that people who cut gears in metal would not use paper templates. In wood, I've cut gears with my CNC Router, that works great for wood precision. In metal, I get a gear cutter set and cut them out of blanks with a lathe/mill. Metal gears tend to be smaller and require much more precision. There's no reason why the shape of these gears wouldn't work, though.