I made some "Trailers" for my Burro crane.
I started out with a Lionel 4 wheel gondola (6-9030) from the Kickapoo Valley & Northern starter set (ca:1970) These cars can be found for a few dollars at train shows. They were made in red, yellow and green. Lionel may have used them in other sets, also.
I separated the body from the base by gently prying the sides of the body until the molded in latches released.
The sides of the car were painted Reefer Yellow. The deck was painted RR Tie Brown. The running gear, wheels and couplers were lightly painted with Rust.
I left one gondola intact. After painting and weathering, I added a ballast load. Extruded foam insulation was cut to size and shaped to the proper contour. I sprayed gray primer on the foam, which reacted causing a rough surface. While the primer was still wet, I covered the surface with ballast. A Woodlands Scenics figure was added.
When hooked up to a Burro crane they make a respectable MOW train for the section gang.
Tom