In the Fated Almanac, the spell for conjuring gamin lists a whole bunch of subtypes, after which there's a box section that says how metal gamin are something different and that only a handful of people know the secret of producing them. Looking at their art, it's pretty different too--the other types all look like spunky imp/goblin things made of whatever element, whereas metal gamin have an almost stonelike body and metal masks, almost like tikki masks.
So who has the secret of making them? Are they an old Malifaux thing? Are they a Union thing? Associated with the Rider?
I'm just curious. The Fated in our game have blasted a big hole in the slums of Riverside with about fifteen sticks of dynamite and toppled a nearby building into the whole, which in turn collapsed that section of sewer into an even older section. Down there in the dark I plan to have them run into this big Pyramid Head kinda' thing called the Organ Grinder, a condemned Nephilim ogre like Killjoy that's borged out with pressure gauges for eyes and chained to an enormous crank that creates creepy freaking music from an enormous subterranean calliope. I'd like him to control some weird monkey like things, but I'm unsure what I want to go with, so metal gamin are one of the things I'm looking into, because they look kind of odd in a cool way. But I want to know more about them first.