Always on the look out for inexpensive ways to goof off. The hapless victim in this case of reckless experimentation is a late era battery 0-4-0 which, in due time will have the rods installed which were left off originally ( I assume) as a economy measure. She is pulling a consist of knuckle and tab two wheel cars that look like they fell out of an Easter basket and the engine is a contrast to what was typical. Personally I have more than enough basic black engines. I used Valspar spray paint meant for plastic use. A fun project...
The next prime candidate is this blah tank car that looks like it was painted with auto primer but of course it's the plastic. Maybe a red or blue..will get rid of the stealth grey. Again, its a really inexpensive case of another way to play.