Jet engines are an awful candidate. The tolerances and material requirements to not tear themselves apart are tremendous. We're talking about turbine blades spinning at 5k-45k RPM, at temperatures of several hundred degrees, and pressures far above atmospheric, and an airstream a few hundred MPH in velocity.
The inspection process for the individual blades, and then then for their attachment to the mount, to ensure that an imbalance doesn't destroy the engine is tremendously demanding.
On the other hand, there is a case to be made for an aim-for-the-stars strategy. If you can build a turbine blade you can build anything. I would have thought compressor blades would be a much more likely candidate, but if they can get this to work, more power to them. And maybe 3d printing will give them options they would not otherwise have: internal bleed air cooling channels that follow the leading edge along its curvature, for instance. It's possible that given completely different design and manufacturing capabilities, they'll be able to make something that can do the same job with different tradeoffs.