I did some work this evening on the 1937 Tip-Top-Tap car etching. There's obviously lots more to do, but here's what I have so far. Every detail is accounted for (which was the important part), but I didn't care about efficient arranging. That will come later. And half-etching fold lines are not drawn yet.

I had to make an important design choice. The steps on the prototypes are much thicker than the grab irons and that left two options:
1. Make two separate frets. One thin one for grabs and a thick one for steps. But this has drawbacks. For one, it would up the cost. But just as importantly, on some cars the steps were bolted to the outside. Here's a postwar modified baggage car.
Milwaukee Road MOW X-459, Ex-baggage 2006, ex-1200 - Underbody View by
J.L. Nelson, on Flickr
I don't see a way to mount a thick step like that. So that leaves the other option.
2. Make folding steps like Trainworx does with their ladders and grabs. That way, pins on the steps can fit into slots on the outside of the shell for those baggage and Tap cars. And for the rest of the cars, the angle is already there (like in my drawing above).
The downside is that the step part will stick out a little bit from the support part, and that's not prototypical. You can't win them all, I guess.