MIT fires a rocket motor made using 3D-printed plastic
 

If you're going to 3D-print rocket parts, you'd want to make them out of metal to handle the stress, right? Not necessarily. MIT has successfully test-fired what it believes is the first completely 3D-printed rocket motor to be made with plastic casi...

https://www.engadget.com/2017/04/30/...-rocket-motor/