There’s a couple out there:

https://guncadindex.com/search?query=p320+magazine

Looks great, but I question how the brace designation would play out with what looks to be a fair amount of surface area.

The term “ghost gun” is a sensationalized media coined term used to excite the easily excitable. The ATF defines DIY firearms as “PMF” or Personally Made Firearms. They are 100% legal in most US jurisdictions as long as you’re otherwise not a prohibited person, and they have been a part of the history of the US since before the US was a country.

As with most things, as technology progresses over time, the barrier to entry lowers. For instance, there was a time in the very recent past where the computer/phone/tablet you’re using to access this site was far out of reach of the average person. But now everyone has access by default. Same goes for hobby level making of things, be they firearms or anything else. Society evolves in parallel with our abilities to understand and create. Some people use it for good, some people do not. That’s a people problem, not a technology problem.

Feel free to hang around and learn. You may find yourself amazed at some of the ingenuity and creative problem solving displayed. The things you learn here can apply to other aspects of life, if this specifically isn’t your thing.