NASA is working on leveraging 3D printing in order to make the Space Launch System more functional and efficient with space travel. Many of the parts that will be used when manufacturing the rockets will be 3D printed, including parts like the injectors which will then be installed into a RS-25 engine model.
(http://www.3dprinter.net/3d-printing-helps-nasa-make-headway-on-the-space-launch-system)
The engineers tested the injectors to make sure they were as durable and functional as the traditional manufactured injectors. Sandra Elam Greene, the propulsion engineer, said “We saw no difference in performance of the 3-D printed injectors compared to the traditionally manufactured injectors. Two separate 3-D printed injectors operated beautifully during all hot-fire tests.” You can read the rest of the article and watch the video of the test here.?