As Gizmodo’s Jamie Condliffe explained:
In these videos, you can see the team from Marshall Space Flight Center in Huntsville, Alabama putting it through its paces. That saw the engine burning fuel at temperatures above 6,000 degrees Fahrenheit, while the fuel pumps supplying liquid hydrogen were as cold as -400 degrees Fahrenheit. With the pump running at 90,000 revolutions per minute, the engine generated over 20,000 pounds of thrust.
A great benefit of using this technology is the time and money saved when these specialized parts don’t need to be made by hand and reducing the number of parts necessary in the first place.
They also appear to be able to take the heat (and cold) just fine.
NOTE CREDIT: http://holykaw.alltop.com/20000-pounds-of-thrust-through-a-3d-printed-rocket-engine-video?gk2