FWIW, today is the three year anniversary of when I started this project.
I designed and 3D printed a license plate for it; even started painting it, but I didn't care for the way it looked mostly because it was too thick and had no back side detail.
So I made another one from scratch. I've used similar processes to this to make other plates.
I started with some 0.005 sheet brass. I cut this blank and drilled some holes.
And then I cut a plastic "rim" from .005 sheet plastic and attached it with clear gloss paint.