As part of a year 'round informal train gang that met Wednesday evenings at Richard Sherry's home in Chicago in the late '80s, I'd seen a photo of the "Silver Sky" dome-obs car on the California Zephyr and thought a PW 2531 could make a reasonable facsimile.
Fortunately, one of the guys worked in a machine shop and told me all I needed was to give him the shell and a dome which I did. A week later I had this. It languished in a box through a couple of moves until a few years ago when it made its maiden voyage pictured below.
I didn't physically make it, of course, but it turned out pretty nice. And I have more plans for this resurrected 2531 in 2019.