N-Scale W24x104 (24" deep x 104lbs/ft) steel wide flange beam. Actual print size is 3.8mmH x 2.0mmW x 96mm, which scales out to 24"H x 12"W x 50'L.
The thin walls were designed for a 0.25mm nozzle and 0.10mm layer heights.
The beam is designed to print in the vertical position without supports.
Glue stick on the bed may be required for adhesion.
The author hasn't provided the model origin yet.