A very simple closed 20ft shipping container for TT gauge (1:120) model trains.

I included the FreeCAD (version 1.0) design in case you want to alter the model.

Printing

PLA and standard settings will be fine, no supports needed on an FDM printer. No idea how it prints on SLA, sorry. (Let me know if you can print it successfully on SLA.)

The container and its locking bars are separate models, so you can print them in different materials.

For the container: simply place it on its flat surface, which should be the default.

For the locking bars: the have a flat side and a featured side - print them lying on the flat side.

It can be scaled up to H0 (1:87) by printing it at 138% of original size. Smaller than TT will probably not print properly. Bigger will emphasize the lack of detail (the twist lock holes and some other details are missing).

Assembly

Put a small drop of super glue on a piece of paper, then use tweezers to carefully dip the locking bars' flat side (just the ends) into the glue drop and then place them on the container door (the side with the more interesting pattern) - there is a space that should align with the handle. See the pictures above for details.