These 3D printers are pretty cool.
However, you've gotta design and create the part you want using CAD (Computer Aided Design) software.
Software like AutoCAD ain't cheap, and the learning curve takes a college course.
Not something the average model railroader is gonna tackle.
If there's something you want done, you'll have to hire a CAD software pro to design it, then you'll have to choose the most durable and strongest plastic to use in the most accurate reproduction 3D printer machine.
Lots of luck. The best and most accurate (in millimeters of specs) 3D printers cost hundreds of thousands of dollars.
There are companies out there with those type of 3D printers that will do it for you if you provide them with the CAD file, but they don't wanna just make one or two items, they want to make a run of several hundred. And it ain't gonna be cheap.
Maybe someday 3D printing (like computers) will be inexpensive and easy to use, but that day won't come for a long time.
