Then you are not up to speed with what the 3D printing world has to offer. You can 3D print full metal stress free parts and chances are very high that if you have flown in an airplane in the last five years that some of the parts of that plane (and I'm not talking about trim here) were made using additive processes.
Rocket engines can be 3D printed, in fact there are some engines that can only be made using that kind of technique due to internal structures.
Yes, real parts CAN be 3D printed and even used successfully.
The printing is the easy part.
The extensive testing and validation that it will actually work as intended and in your situation is the hard part.
Skip that hard part, especially for anything that flies, and you are risking lives, both those in the air and on the ground.
Seriously, just because the specs on the label say X and other docs say the running temperature is Y, does NOT mean it will work. Take the measurements in your situation, test the thing extensively on the ground.
Then, maybe, it'll be worth flying. Or, you'll be there after some hours of testing saying: "good thing I didn't try to fly with this", and still have a usable aircraft.
Rocket engines can be 3D printed, in fact there are some engines that can only be made using that kind of technique due to internal structures.