Good post. I like to do customs myself(as well as stock), mostly because I can and it's fun, although I'm very careful that I use only top quality stuff (i.e. Langdon, Apex, etc), or top Quality Smiths (Yost, MARS, etc). And I test the hell out of stuff, because that's also fun(and necessary.) As an engineer, I eat this shit up.
That said I'm an engineer(well manager now, so I've had my management lobotomy) who has helped build a business (with many other people of course) that's worth a number that likely now has a B or two in it. Ole Gaston himself wasn't much of a business in the firearms space when he started, and he changed the entire industry. My own product has likely changed the way computing, security, and networking happen.
A lot of the best advances come from some nobody that pushes the limit, sees those limitations, and tries something new. A lot of them fail. Heck, probably 98% fail. But for all those, the Glocks, Randy Lees, Bruce Grays show up, become experts and help change an industry to varying degrees. Don't knock'em, just know their place. Play with them like you did, let others do the initial testing. You'll learn something. If the manufacturer is smart, they will learn too. I remember when Magpul mags came out. A freaking (injection?)molded piece of plastic...Good on'em. I love that stuff.
Those garage machine shops are mostly dumbshits. But there are some diamonds. And those sometimes become the Gaston Glocks (who I believe literally started in his garage).
N