This whole thing makes me laugh. Making one's own firearm has always been within the reach of people with specialized skills. Add working with 3D modeling software and rapid prototype machine to the list of skills that can get one there. It's no more fearsome than someone learning blacksmithing and making a musket.
I've seen photos of the parts of this gun. In FDM it will break. A handful of cycles I think if one is lucky. It's about as fearsome as a zip gun. Replace about half dozen parts with metal and it will work longer.
The difference is that today there is a vast majority of people who are full of fear and have no clue how to make things or how things are made. Bunch of helpless paranoid children. In the 1950s the guy down the block was machinist could make his own gun and people were like 'so what?' to 'that's neat', but today people are afraid. lol.
We got to get people back into the business of making things before this whole country falls to crap.