This is a highly-detailed HO-scale intermodal container, printed in one piece.
It is compatible with PIKO containers and wagons as it has small pins at bottom that fit respective holes in flatbed cars. If you do not need them, just cut them off (their printing time is several seconds)
The real dimensions of the container are: L69.8mm, W28.7mm, H28mm (height not counting the pins)
On the photos you can see it with a PIKO stock yellow one.
There are two versions: one with flat roof (easier to stick to print bed) and corrugated roof (more realistic)
UPD 23 Feb 2019
I've added corrugated top and turned the model upside down. The STL file should be printed as loaded.
Update 18 Jul 2019
Wall corrugation is more realistically correct and symmetric.