There's a detailed story on Road.cc describing the process of producing a metal dropout bike part using DMLS - Direct Metal Laser Sintering.
Producing bike parts is much like any other product; prototypes must be tested and final versions become mass produced. The problem is that producing prototypes has been time consuming and wasteful of resources.
This particular experiment involved creating a prototype dropout that, once welded to a cyclocross frame, would be the test version of a potential 50 bikes using this method.
The equipment used to product the dropout was the EOS M270, which uses fine metal powder as its print medium. Similar to other powder printers, the EOS uses a bed of powder and laser-fuses each of the object's layers in succession to develop the whole part.
We're wondering what kind of innovations might emerge once the designers leverage the full capability of 3D printing approaches, since "impossible" designs now become possible.