"Engineers developing NASA's next-generation rocket closed one chapter of testing with the completion of a J-2X engine test series on the A-2 test stand at the agency's Stennis Space Center in Mississippi and will begin a new chapter of full motion testing on test stand A-1.
... The March 7 test, which set the short-lived duration record, was remarkable for another reason in that it marked the first time a 3-D printed part was hot-fire tested on a NASA engine system.
The prime contractor for the liquid engine, Pratt & Whitney Rocketdyne of Canoga Park, Calif., built a maintenance port cover for the 10002 engine using an advanced manufacturing process called Selective Laser Melting. This construction method uses lasers to fuse metal dust into a specific pattern to build the needed part."