It's been legal since the dawn of the USA to manufacture your own firearms.
A criminal who is otherwise not legally able to acquire or possess a firearm is not going to care about 3D printer laws. This only impacts the law abiding.
> There's already far too many nutcases who own far too many guns - allowing them to print their own guns and ammo to avoid being on some sort of watchlist is just a really slippery slope.
There's no federal requirement for a "watch list" for owning a gun. There's background checks for transfers of firearms, but even those are not applicable in all cases (e.g. a father can transfer a long gun to his son in most States without any paperwork at all).
Manufacturing your own ammo is legal across the entire country. There's no registration requirement or any paperwork whatsoever needed.
> I'm all for people owning guns, I support the 2nd amendment vigorously,
Let's be honest here, you clearly don't.
> but there's a reason the words "highly regulated" appears in the 2nd amendment.
The words are "well regulated" and they don't mean what you think they mean. In 18th century American English, the phrase "well regulated" means well equipped.
It's saying that people should have lots of guns!
> Sick and tired of fringe nutcases (supported by the gun lobby) saying any and all regulations are a threat to the freedoms we all enjoy as Americans.
The problem with new firearm regulations is multi fold, but the main problems are:
1. There's plenty of existing regulations in place that are not being properly enforced.
2. The majority of new regulations are bans on cosmetic features or simply make things more inconvenient for law abiding gun owners.
3. Anything that was previously considered a "compromise" turns into a "loophole".