Bruce,
Special Shapes has 5/32 (.156") & 3/16" (.187") H beams in brass, along with Evergreen that has the same size in styrene. 5" scales out to .172" so when I order more styrene I’ll order one or two of each size and see what it looks like.
I’ve debated the whole build where to start with brass or styrene, and I choose styrene for a couple of reasons; one it’s slightly cheaper and easier to get the CFO approval; second this is my first major rolling stock scratchbuild and I wasn’t sure how well I could read the drawings and ‘translate’ into a 3D model and I’m comfortable working with styrene; and finally the most practical reason is that I don’t have any of my soldering stuff, or machine tools, or space to work with me at the moment. My wife and I moved from Washington State 4 years ago so I could go to grad school in Montana (now we are in S. Idaho, with me as a first year teacher) and my workbench for the last 4 years has doubled as the computer desk, sewing table, paperwork pile, school desk, etc. I’m hoping to find a more permanent job back in Washington so that we can set up our house again (and my work bench).