Inspired by Tony Thompson, this is a printable girder load for a 40' Gondola in HO scale.

I used the bridge creator this is re-mixed from, zero'ing out enough parameters to effectively remove the decking.

Two versions of the part are included. In the end, I used the v3/thin version, for which the relevant parameters are shown.

The difference between the two is that the SCAD for the v4 version has been hacked to double the thickness of the steel plates. I did this because at the nominal thickness the part was a stringing test that my FDM printer failed when I used an 0.4 mm nozzle.

In the end, though, I used the v3/thin version and printed it with an 0.2 mm nozzle and got almost no stringing. For an 0.2 mm nozzle, each plate is made with two walls, instead of one with the 0.4 mm nozzle.

Cura complained a bit about the geometry of the part not being closed, but it seemed to print and slice just fine.

I was also very pleased with how little layering is evident, though some cleanup with a hobby knife was necessary on the underside of the top flange, where the filament is bridging. Fortunately, this region of the girder is difficult to see when the car is running on the layout.

Two coats of spray paint primer and another two coats of spray paint make it look pretty good without blurring the details too much.

The cribbing was made from cut-up coffee stirrers. In addition to being a nice detail, it keeps the girder centered within the gondola and prevents it from tipping over easily. The cribbing was glued to itself and the girder with PVA (white school) glue, which is nice because it dissolves in water.

It would have been interesting to put decals on the girder, but I've not yet learned how to do that.