As compared to the output from a $600 3D printer... one could currently make what I would actually consider an actual “functioning firearm” quicker, cheaper, and more durable using parts that anyone can find at your nearest home improvement or hardware store.
It is of course currently possible to produce high quality firearms parts at home using relatively inexpensive or homemade CAM Milling Machines. I doubt whether anyone on the Philadelphia city council has even a rudimentary knowledge or understanding of gunsmithing.
I reload my own brass so I have a good understanding and respect for the pressures created by even small caliber pistol cartridges. It is a pastime that requires precision and attention to detail to avoid catastrophe. A couple of grains (1 grain = 0.06479891 grams) too much powder and a perfectly good high quality pistol can blow up when fired. I do not believe that the output from a $600 3D printer is going to be reliable or predictable enough anytime soon to safely be used as a firearm.
The DefCAD Liberator design (since improved on) actually works for many dozens of rounds until stress cracks start showing up on the weapon, indicating you need to stop using it. The one that blew up in testing was using a 5.7x28mm PDW round instead of the .380ACP the thing was designed to handle. It does not explode without ample warning with .380. And after all, you only need a round or two to ‘upgrade’ to a ‘real’ arm.
Yes, you can make a zip gun out of home improvement supplies. But if you do that, there’s invariably video records of you buying the pieces, if not computer records from your electronic transaction these days. And no, paying cash will still not stop the video records (which are indexed to purchase times now!) So if you have to abandon it after using it, there’s a pretty good chance they will be coming to look for you. This is what has these people scared: With a 3D printer there is *NO* record they can try to track back.
Also of import - the Liberator isn’t just proof of concept, there are people still developing and producing them. These variants and more are out there now.
Liberator Compact: A smaller more compact version of the Liberator, with a non-removable grip.
Liberator Hydra Rifle: A Liberator with a 16” barrel, vents to reduce pressures, and a removable stock.
Liberator Pepperbox: This design gives the Liberator pistol four chambers and acts similar to a single action revolver.
Cerberus Liberator: A Liberator that holds a long string of barrels, allowing for faster reloading.