I finished painting all track today, and started painting the turntable. The well of the turntable, which was a sandstone or khaki color, is now gray (I simply used Rust-Oleum Flat Gray Primer).
Once the primer dried, I used a Testors Rail Brown enamel paint marker around the turntable rail:
I also used the same paint marker on the rails, spikes, and plates of my track to differentiate the color from the rail ties. This took several applications and almost four hours! I am pleased with the result, though!