Who did you receive it from and who was the seller?
As already stated above, no requirement for a seller.
The law states "...obtains a firearm, rifle or shotgun or machine gun from
any source within or without the commonwealth." I could argue that the manufacturer is 'any source' even if it's yourself. Thin point, yes.
I can see your point, it's just a bit too grey to bank on in a court system predisposed to your guilt on gun issues.
The law also states "...obtains a firearm, rifle, shotgun or machine gun from any source... ...
and receives such firearm..."
So you could also argue that you can't both manufacture it and receive it but that's also a pretty thin point on which to base the entire case.
Then... If you never received it then how is it you have it?
Well, I received the parts, yes but it wasn't a firearm at that point. Then I manufactured it...
So you received it after you obtained it by manufacturing it.
Then you tell me who I received it from.
You received it as a result of the manufacturing process.
The manufacturing process is not a person or place.
But it could be a source.
And round and round... Chit makes my head spin.
The upside is that first offense is just civil.