You know, the more I look at the photo of that boxcar, the more it looks like laser-cut Laserboard (resin-impregnated paper product). So maybe it is similar to what they used on that hopper.
Yes, I'm that good with the laser that I can mimic injection molded plastic . LOL The 96K has laser cut roof walk...we don't use it on any other car at the moment. I hope to revisit the hoppers later this year and see if we can retro those as well. My list is long so be patient.
Joe