Two companies, Dynetics in Huntsville, Alabama, and Aerojet Rocketdyne of Sacramento, California, have begun building replacement engines in lieu of the Pentagon getting the RD-180 from Russia, and they’re using 3D printing to create a major engine component -- the pre-burner. As the US has backed away from previous, positive trade relations with Russia following the latter’s invasion of Ukraine, the Pentagon has been seeking alternatives for producing the RD-180 rocket engine that plays a critical role in the launches of the Atlas V rocket, a key component of the military’s reconnaissance, communication, and navigation satellite program. Read more in the full article: http://3dprint.com/20496/3d-printed-us-rocket-engines/ ‎

Below is a picture of two RD-180 rocket engines, which currently use Russian technology and are transitioning toward 3D printed components: