The 1st item on this list is 3D metal printing, and includes this nice quote:
https://www.technologyreview.com/lists/technologies/2018/
Replace aging car with aging ship...In MTU, as I mention in the Scout Waystation guide, huge 3D printers / makers can produce a large selection of stuff they need w/o having to ship things in."In the short term, manufacturers wouldn’t need to maintain large inventories—they could simply print an object, such as a replacement part for an aging car, whenever someone needs it"
https://www.technologyreview.com/lists/technologies/2018/