Most of the shelf 3D printers just read g-code: https://all3dp.com/2/3d-printer-g-code-commands-list-tutoria...

Simplified they just get thousands of commands from which position to which position to move a toolhead, at what speed and how much plastic to extrude.

They would have to re-create the 3d model from those commands and compare them to banned ones? But then the firmware is often open source or at least can be flashed. And also how would the printer know if it's a toy gun or a real gun? Or just a part for a gun.

Paper printers / copiers refuse to copy money because the government controls the source, the paper money. They add small dots on them.

The government can't add those dots to self made 3d models.

I would hope printer manufacturers would not ban you from printing certain items! I would never buy from any 3D printer company that did that.

Yes, this is a thing. Supposedly such a thing was used in a recent attack. 3D printers are not able to determine intended operation of their printed output from their print job inputs, whereas counterfeit money has no legitimate purpose, so anything that looks “close enough” for an automated system to detect is probably close enough to fool a human if passed to them as if it were the real thing. I think preventing counterfeit money is a broad enough social good/benefit that a broad cross section of industry, government, and private individuals and groups have decided to work together to make it harder to produce. I don’t see who is harmed by this, besides people trying to print their own currencies for their own purposes, some of whom aren’t trying to make counterfeit copies of actually-existing currencies, but I think they are already going to have to worry about the counterfeit problems themselves if their currency is used outside of controlled conditions by trusted parties.

>>Andy Greenberg has been reporting on ghost guns for more than a decade. He first used a 3D printer to assemble a gun in 2015, and he says that today’s process is not only faster but cheaper. We talk to Andy about how he legally printed the same gun Luigi Mangione allegedly used in the alleged killing of the United Healthcare CEO last year, and whether US law is keeping up with the technology of 3D-printed guns.

Here is a link: https://www.wired.com/story/uncanny-valley-3d-printed-untrac...

There are two parts to a gun.

The "explody bit" that needs to survive intensive pressures, which boils down to a carefully machined barrel (rifling is optional) and a firing pin.

The "comfort features" that make it easy to hold that barrel in a human hand, that direct the recoil to parts of the human body that can better handle it, that hold the ammo in a way that automatically feeds the next bullet (spring magazine) and that makes it easy to press the firing pin against the munition (the trigger).

The latter can easily be 3D printed.