As reported across a number of outlets, but most accurately here, NASA used a "selective laser melt" printer -- one that uses heat-generating lasers to form and fuse various metallic powders into a solid design -- to fabricate a rocket injector. More importantly, NASA used this technology to make a working rocket injector. A report on the rocket's development and testing was released last week, in which NASA states that a rocket manufactured through traditional measures would take more than a year to produce, whereas this 3D printed rocket was developed across four months. NASA also noted that producing the rocket through 3D printing methods netted a 70% reduction in costs.
Granted, every article declaring 3D printing to be the wave of the future glosses over the fact that its use is presently limited to custom builds. There is no setup for mass production via 3D printing just yet, so its real effect on supply chains and cost savings is not something that can accurately be measured at the time of writing. It is clear, however, that a large portion of manufacturing research is being focused on 3D printing, and the technology will eventually have an effect on manufacturing and supply chains. The only question is "When".