Not interested in having anyone do the work or paying someone to mess up my work, I have a primitive pantograph engraver that does exactly what I want, and I have enough hot tips that keep me busy enough, lol.... Somehow you don't want to see that I am not telling anyone to engrave a copyrighted trademark name on a gun, I would not, I only answered a question asked about an engraving method I prefer and use, plain and simple, please stop reading extra into my response and lets not have fruitless arguments on trivial matters.
Modern CAD-CAM technology means that you can disassemble an AR-15 (or any other gun), scan the parts into a fab shop's computer, and the machines will make a duplicate!
In theory, the durability of some parts might be an issue, pressure or high wear factors. In any case, unregulated parts are not really cost effective to duplicate, you only need to duplicate the lower receiver, that's the part with a serial number, and when you create a firearm for yourself, you are not required to put a serial number on it.
Guns are not registered here, but if I'm not mistaken all firearms made now must have some serial number on it somewhere anyway, even if just making up one. Am I correct on that? - - - Updated - - - Are you sure about that? The reason I ask is I have a 1918 that was a put together and it does have a serial number on it - but was builder stamped on an easily removed component. A veteran gun seller of military firearms said that is a HUGE no-no and that the serial number must be on the main frame. He has adamant about that.
BATFE will tell you the same thing, you can make a firearm for personal use, and it does not require a serial number, if you want to be able to sell it, you must get a BATFE form to make a firearm. Every now and then you will find commercially made rifles and shotguns, and even some pistols, predating 1968, that have never had a serial number.
I thought about doing one with 80% lower---but just finished doing my own complete build with Aero-Precision advanced upper on top of a generic registered lower. I did this with a Primary Arms red dot for about $1,000. My thinking is that if it ever got so bad that the government began looking at all the millions of ATF form to begin nationwide gun confiscation, that the nation would be at a tipping point---and my registered un-PC guns and I would no longer be a priority going after.
