Ghost guns

Awhile back,  there was this post that linked to these things called "ghost guns", which are untraceable, yet legal guns.  So, I get this brilliant idea that I may be able to make these things and sell them.  They are not legal to sell or transfer though, unless you have a license.  So now I am wondering what it would take to get one of those and whether or not it would be worth it to obtain it.  I'm thinking most likely that the guns will have to be made traceable before they can be sold, though.  Not to mention that I would have to do background checks or obtain the info so that background checks could be made.  What would be the reason why people would buy these guns?

Not to mention that a lot of equipment and expense must go into this first before you sell even one gun.  Something to think about, though.

Update:

I managed to obtain a copy of an application for a license to sell firearms.  What it requires may be rather complex to execute because it requires a physical address, which may be hard to obtain.  Although "da Ranch" is indeed a physical location, the research that I've done so far suggests that it may be hard to obtain what is called an "RFD" set up so that mail can be delivered to "da Ranch".  Without this, it may be hard to do business at "da Ranch", which may necessitate doing business in town, which could prove to be a pain in the neck.  A little more footwork on this may yield a solution, hopefully.

The fee is $90, which expires after 3 years.  Not that bad.

Update:

Further research leads to discouraging words.  Some of what is being sold as not a firearm is actually going to be considered as indeed a firearm, and the work that comes afterwards is just bunk--- meaning trying to fool the public.  In other words, it's a scam.  You get mixed up with this, and you just may be sorry.