I have been wanting a centerbeam flatcar to run on my layout. So, I set out to design one and print it on my 3d printer. I had a couple of S Helper Service flatcars without a load and added the printout to them. The design copies current prototype cars, but is not a scale model. It is more of an approximation to fit the existing flatcars.
And I also printed it in brown.
They look pretty good and are, at least for me, a reasonable approximation of the prototype. I am running them empty but may add a load later.