I built my transport box a few years ago from some salvage 1x12, 3/4 plywood, & small channel iron. I painted it all ferguson grey, so from a distance it looks fairly authentic....
I should know better than to leave anything made of wood sitting on the ground around here, but I did & got the expected result....
Had one last piece of the salvage 1x12 left, it was just enough to do a decent repair. Not as pretty as it was, but it's back in service.
Needs a coat of grey though.