Norman,
I think you are asking three different questions. Professional 3D Design Services are available in both countries. 3D Printing Services are available in both countries. People who are knowledgeable in locomotive designs and specifications are available in both countries. One individual to fill all three requirements will likely be hard to find. Individually a Google search will find lots of Design Services and lots of Prototyping shops that provide 3D Printing services. I am not sure how many modelers will claim the locomotive expert hat for other people.
This is based on my experiences as both a model railroad hobbyist and as a 25 year experienced 3D Professional Designer. The best answer I can offer that answers your original request is look up Kirkville Locomotive Works on Facebook.
Good luck Norman.