If someone wants to get hold of a gun, they will and no amount of laws or enforcement will ever change that.
> Except the lack of guns
The benefit of 3D printing is that at least you have a better chance tracing a home printed weapon than you would an illegally purchased street firearm with no serial number.
> Except smart filesharers already can't be caught
There will never be a lack of guns. America is too big to police efficiently. The drug war which has well and truly failed is a perfect example of this.
Filesharing is different. Printing a gun from a 3D printer requires materials, materials which can easily be traced back to their purchase point of origin. You could argue said materials could be obtained on the black market as well as the printers, but you have a better chance of tracking a created gun back to a particular type of 3D printer. I'm not saying it would be that reliable, but at least law enforcement agencies would stand a better chance than they currently have. Tracking a gun without a serial is like treasure hunting in the pacific ocean without a map.
> Except the lack of guns
The benefit of 3D printing is that at least you have a better chance tracing a home printed weapon than you would an illegally purchased street firearm with no serial number.
> Except smart filesharers already can't be caught