...the other side is pretending that because a gun can be made in someone’s home then there is no reason to restrict any kind of access to guns period
I do not think this is a correct representation of the argument. I think there is a dimension of time here. The argument would go like "since a gun can currently be 3d printed at home, and the 3d printing technology is rapidly and irrevocably evolving, there is no way in the near future you could prevent someone from fabricating any gun at home, so it's kind of fruitless to keep forbidding them. If you would instead keep not so rigid laws regarding both possession and display of firearms, that would be a more efficient venue because people would take the necessary effort to be legal, and they would also be able to defend themselves in case another armed opponent intends to go crazy mass-shooting."