Unreal intake manifold cost

3d printing metal parts, especially manifolds, would still require a lot of machining to finish the part properly. Porosity is still a problem too, especially in aluminum.

The process in metal is called selective laser sintering, and it's not cheap. It's a lot farther off than 4 years to making production parts too.

I've seen custom modelled manifolds printed, and they work, but you're talking several thousand dollars for a log type manifold for a straight 6 type engine.

3d printing requires specialized metal powder for this process. It costs more than casting stock does. It will never be cheaper to print a part. The only reason to do it is super low volume (aircraft, typically) or geometry which can't be made another way. There's plenty of ways to make manifolds, no reason to reinvent the horse here..

It would be far more economical to print a wax pattern and have it cast than it will ever be to print it.