I want a through hole component for 1/4" jacks. How does a component get standardized and manufactured? Is this an attainable goal for a normal human, or does it have to go through some kind of standards body, etc…
Well, start by designing a CAD model - it’s up to you whether that model conforms to certain standards. Then depending on what part it is you have to set up QA, compliance testing, bulk manufacturing, documentation, packaging, shipping…
A lot of time, effort, and money for a relatively tiny amount of gain. For the amount of money you’d put into it, I would go and buy a 400 module Eurorack setup
Was it @popflier that had a load of pots manufactured?
I did have pots manufactured by a company in China. While I did have them manufactured based on products that they already offer, they were willing to do some minor modifications. They could manufacture them with/without tabs or make them in different values than what they listed as available on their site. Beyond that I think that I could approach them with a design and they could probably manufacture it, provided that what I was asking them to manufacture was similar to something they already make. It’s likely that they would require a significant sized order though of the final product (1000+ units) in order to make it profitable and worthwhile for them.
On that note, I stil have like 200 pots left of both B100k and B10k to get rid of so please someone order some!!
I think your big enemy for a completely custom part will be the set-up costs. For example, you probably want to give the jack socket some sort of plastic body. Those will need to be injection-molded, which requires machining of a mold. Such mold can run you $10k+ easily.
Maybe a more viable option would be adapting an existing part. Maybe you could rip the metal parts out of an existing socket, and combine them with a 3D-printed body?
 now I’m thinking, the type of jack sockets commonly used in guitars is that shallow. Maybe you could start from those.