I'm willing to bet the quality of a lot of these is shite, though. Plus people in the US would most likely want to buy from a seller in the US (faster shipping + implied better quality).

There is a solution to so many problems here (creating usually unavailable parts for machines/devices/products) but the problem is knowing which parts are in demand and currently have no supplier.

A maker would need to have an interest or hobby in such a device & discover a need for the item for it to come into fruition. But just think of how many general 3D printed parts could be printed as solutions for so many products out there that are going unmade.

I meant that there must be Chienese people doing the same thing people used to do here when domestic factories a thing.

I was not commenting on the quality of the work. BTE, saying the Chinese quality must be automatically shite is a ridiculous idea.

Not all Chinese stuff is bad, but there's so much bad stuff that it's hard to know what's good. "Chinesium" is an accurate description of the situation.

Same with American made products. Have you driven a Chevrolet lately?

In the case of American-made products, it's easy enough to do the research to determine if a product is good, or even try it before you buy. I don't know how good Chevys are these days—the newest one I've driven is a 2005 truck—but they're a known entity and you can test drive one for free. Ordering something online from China is a stab in the dark.