Neato:

NASA 3-D Prints First Full-Scale Copper Rocket Engine Part

It’s come equipped with internal cooling channels; this sort of thing is kind of the dream of rocket designers. A thin-walled highly thermally conductive combustion chamber with built in regen cooling? Sign me up! But don’t start planning on your rocket powered cars just yet; neat as it is, there are still some problems. First: cost.

A selective laser melting machine in Marshall’s Materials and Processing Laboratory fused 8,255 layers of copper powder to make the chamber in 10 days and 18 hours.

A terribly expensive machine ran (presumably non-stop) for a week and a half to make one part. The direct cost of the part wasn’t given but I’d guesstimate somewhere between “A Lot” and “A Whole Lot.”

Second: quality. If you look closely, you’ll find not only the rough surface standard with 3D printed parts, but also some spots that look like something went a little off, like the part slumped locally:

With all the nitpicks, though, the importance of the piece isn;t the piece itself, but what it represents. A combustion chamber like this would be essentially *impossible* just a few years ago. In a few years more, the quality of this sort of chamber will be much improved, while cost will go down.