The process had been used previously to produce parts for military aircraft, but this the first time it has been used this broadly for a production commercial plane. There are strict airline safety standards that have to be met and these new processes require new testing procedures.
It’s a milestone, of course, but given that the typical commercial aircraft has over 2 million parts, these 1000 parts represent less than 0.2% of the parts no the plane.
3D printing is typically used more for prototyping and one-off projects than for production. I’ve been enjoying learning about 3D printers at home – I’m still in the tweaking and tuning phase, learning about the characteristics of the material, how to design for 3D printing, etc. - it’s a lot of fun.