Unreal intake manifold cost

MopaR&D said

At this point I'm just gonna wait for metal 3D printing technology to get to the point where we don't need castings anymore. It's pretty close maybe 2-4 years out? The tech is there it's just still a bit too expensive for the common man. And intake manifolds would be easy because they don't have moving parts and aren't under much stress. People are already 3D-printing custom plastic intake manifolds for EFI applications.

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I know nothing about 3D printing, but the process is really interesting to me. Could you answer these questions that immediately come to my mind?

1. In metal 3D printing, is there welding involved? Otherwise, how is the filler (if that's even the word) deposited?
2. How does one go about creating a map or file for a 3D-printed manifold?
3.Could someone do copies of already produced manifolds without risk of copyright infringement?