Add detail to boxcars with open doors.  Add some crates, boxes, tarp load, or figures to your boxcars that have open doors.  There are even lumber, barrel, or bag loads you can place into an opened boxcar.  You can even add a fake wood flooring to add more detail.

Micro-Trains Military Barracks Build by Modelersguild.com

Building this Z-Scale kit was a real pleasure. The parts fit nicely, the materials were right, [ ... ]

Micro-Trains Farmers Co-op Build by Modelersguild.com

I am definitely getting better at Z-Scale. Another Micro-Trains kit, I am liking these more and [ ... ]