Easier Metal Printing
While plastic is a popular material of choice for many model railroading applications, metal is also used frequently where a stronger material is required. The obvious example is the use of brass and other metals in locomotives, especially for scales larger than N.
Even in pewter form, traditional metal parts can get expensive. And finding metal replacement parts for locos that haven't been made in years? Forget about it!
3D printing metal has been around for a while, but it isn't always as consistent as plastic and can get expensive. The good news is, as we've seen with other emerging technologies, it has been improving over the years.
I'm posting a link to this article because many model railroaders would be interested in the prospects of printing their own metal parts. It sounds like researchers have figured out a way to use bulk metallic glasses (BMG's) to print in much the same way as many 3D printers print plastic. The next step is to make BMG materials more widely available. This could open up a whole new world for model railroaders!