Here's are a few of the freight cars on the layout; I've been building models since my early teens and got into 'serious' model freight cars in the late 1970's. I went to high school in north Kansas City and Charlie Winter's lived only a few miles from my parent's house. While I knew Charlie had an extensive collection of steam locomotives negatives, one evening he mentioned his freight car and caboose negatives and I was off to scratchbuilding many of railcars in the photos. As the years have gone by the scratch built models gave way to resin models or more state-of-the-art plastic kits but the introduced me to researching the prototypes and making the cars look as weathered those I'd seen in the many rail yards I'd worked in while traveling on the Mopac.
Al Westerfield approached the Mopac Historical Society on bringing out a model for the Kansas City NMRA convention. I helped him with photos and plans which allowed him to bring out the Mopac 40' automobile car in his resin line.
Many of my cars are plastic from Branchline, Proto 2000 and Accurail but I enjoy building resin kits due to the variety they introduce to a train. Besides seeing Al Westerfield's kits, I have Martin Lofton's Sunshine Models, Yankee Clipper and Speedwitch kits. The laser kit of the Mopac side door caboose is from Lake Junction Models as standard assigned caboose on my local.
Weathering on the cars depends on the age of the car compared to when the layout is set in 1954. I use weathering powders, oil paints, pastel pencils and colored pencils. Before computerization on the railroads, railcars were classified by routing cards attached by a 'mud hop' (yard clerk) or switch foreman using chalk marks. You'll see examples of this on most of my models represented using a white pencil or white ink.