Your question is pretty broad in scope which makes answering it a challenge.
Realize that whatever answer I give you, you need to contact your local ATF Office and get an opinion from them directly.
ATF Branch Offices are actually quite helpful when you call and ask questions. They aren't the Gestapo and your relationship with them when you call to ask questions isn't adversarial.
Realize that YOU are calling them to assure that you are abiding by the law and in my experience they treat you accordingly.
It's much like asking a cop for directions.
According to ATF:
Generally, a person should obtain a license as a manufacturer of firearms if the person:
1) is performing operations that create firearms or alter firearms (in the case of alterations, the work is not being performed at the request of customers, rather the person who is altering the firearms is purchasing them, making the changes, and then reselling them);
2) is performing the operations as a regular course of business or trade; and
3) is performing the operations for the purpose of sale or distribution of the firearms.
If you're making a firearm for your own use and have no intention of selling it, you do not need a manufacturers license.
per provisions of the Gun Control Act (GCA) of 1968, 18 U.S.C. Chapter 44, an unlicensed individual may make a “firearm” as defined in the GCA for his own personal use, but not for sale or distribution.
So it appears that you may make your own gun for personal use as far as ATF is concerned.
GCA 68 defines firearms as:
“…(A) any weapon (including a starter gun) which will or is designed to or may be readily
converted to expel a projectile by the action of an explosive:
(B) the frame or receiver of any such weapon;
(C) any firearm muffler or silencer; or
(D) any destructive device.
Such term does not include an antique firearm.”
It looks like you can make your own silencer as well. BUT keep in mind that YOU are going to be the person answering to the guys in bad suits if this is wrong, not me; so I would make that phone call.
Also, we only discussed the question from the perspective of Federal Law, you have the State and Local laws to deal with too.
That should make it about as clear as mud...