This is a design I have been looking at doing for a while and whilst working on a very similar design for my model railway club I adapted it for others to use.
This is formed of two versions of different lengths. I have produced both as a single item that can be printed on a resin printer. I have also printed girders that can be printed on an FDM printer flat and then glued together (please see photos). I will label it as Resin and FDM but you can print as you like if needed, The two sides for the FDM are identical so only one side is included per length.
Design 1 is 150mm long approx.Design 2 is 107mm long approx.
Its height is about 27mm high and about 4mm deep when fully printed. 27mm equals 2m in real life.
I have tested the resin design on a AnyCubic Photon M3 using ABS Like resin. The FDM design has been tested on a Bambu Labs A1 with a 0.2mm nozzle and a layer height of 0.06mm, due to the complexity of this design I would recommend using a 0.2mm nozzle rather than a 0.4mm nozzle.
I recommend 3DLAC Spray to help secure the print to the print bed whilst printing (FDM), it also helps release the print after printing has finished.https://amzn.to/4cxPybm (Amazon)
I use AnyCubic Water Washable Resin for most of my items but use AnyCubic ABS Like Resin for anything that needs to be stronger and tougher.
use this link to join CGTrader and download my designs.
https://www.cgtrader.com/designers/PJD1974?referral_id=3218445