If you happened to download the 3D printed handgun models before the US government confiscated them, it may be time to remind you of safety concerns should you attempt to 3D print this item.
The ease of 3D printing and the sudden availability of a working gun model meant that some people will attempt to print the handgun merely out of curiosity. We say: Be Careful.
Aside from various legal concerns that may vary considerably and severely from jurisdiction to jurisdiction, there are technical concerns. A firing gun is a controlled explosion. There's significant heat and mechanical stress applied against the gun, meaning several bad things could happen.
The stress and heat can obviously cause a catastrophic failure - an explosion - which could fling sharp and hot bits at the operator.
Another issue is the material used to print the handgun. While Defense Distributed has been experimenting with relatively strong ABS plastic, some 3D printer owners may choose to print in whatever happens to be loaded into their printer - which might be totally inappropriate for this purpose. Some materials are actually explosive and/or flammable themselves.
Needless to say, this is a rather dangerous activity. Don't let your curiosity get you in trouble.