There exist metal 3D printing technologies, but usually the mechanical properties of the finished material are not as good as an equivalent cast version, although can be as good as about 80%, in terms of Youngs Modulus.

At the cheap end of metal 3D printing, shapeways.com will make you stuff out of stainless steel at $8.00/cm^3. More b2b companies will provide more detailed mechanical info about their process and the results.

A site close to my hobby interests is http://rocketmoonlighting.blogspot.com , where this chap has printed a rocket engine, complete with internal regenerative cooling channels (where you keep the combustion chamber and nozzle cool by pumping the fuel in channels around it before it gets injected in the chamber). I think it's wonderful, and is a reason I'm excited by 3D printing. Also, being able to print Printed Circuit Boards, i.e. printing copper tracks onto a fibreglass substrate, would be a serious boon.