Lionel Terra Cotta is a difficult color to match with modern paint. It was used by Lionel in the late 1920's to early 30's, so is a lead-based paint. Lead makes the finish stronger, but also gives it a muddy quality. I believe lead was banned from finishes in the 1960's. Modern finishes are difficult to match to lead-based finishes because modern finishes lack that "muddy" quality. Modern spray-can finishes also are more primary type colors or metallics. The best you can do from a can, is take the piece you want to match to a big store like Lowes and match as close as you can to the color on the cap of the can. Auto parts stores should also have a good variety of colors to choose from, but may not have Terra Cotta. Have you ever seen a Terra Cotta Ford or Toyota??? Also, we all know the cap color and patina do not always match the paint color in the can. One way you can achieve a darker or muddy quality to the finish is to first paint with a black, gray or rust-color primer. Experiment with progressively thin to thick coats of your top coat to get close to the desired color.
Another reason you will have a hard time matching original Terra Cotta finish, is that Lionel always applied TC paint by dip-painting, which results in a thick, sometimes uneven finish that can include runs. Spray-painting results in different degrees of "orange peel" patina, depending on thickness and conditions when it is applied. Paints can be special-ordered in cans that can be used with a spray gun. I have never done this, but imagine the cost-factor would require a large minimum order, and your supplier may have the same problems matching a muddy color.
