Watch This When You're High - How Does 3D Printing Work?

Since the Luigi Mangione story broke last week, and the details surrounding it started to emerge and become clear, one of the things that's stood out the most to me was the supposed "ghost gun" Mangione allegedly "3d printed". 

I've heard of 3d printers over the years, but I've never seen one in person, or watched one actually work. So I had so many quetsions. 

First off, how the fuck do these things work? How are you able to produce something in your bedroom, that is capable of firing a bullet that can then kill somebody. How can society balance the freedom of innovation with the potential misuse of 3D printing in crimes like this? If he did in fact use a gun he printed to kill that CEO, who should be held accountable: the manufacturer of the 3D printer, the person who created the design, or just the person who pulls the trigger? Are there reliable methods to track or trace 3D-printed ghost guns, or does their nature inherently allow for anonymity?

Here are some crazy videos of things these machines are capable of- 

Keep the suggestions coming. Keep them classy. No butt stuff.