It was pointed out to me that the Bird of Prey in Balance of Terror (and The Deadly Years, thanks to stock footage) was a new ship. This was said in the Balance of Terror dialog. The ship was sent on a covert mission into Federation space, so it may not have been fully painted when it left its dock. Also, there’s a good possibility that later ships in the class may have had more markings. So, aside from the Balance of Terror version, I also did one with more markings.
I also added some impulse engines to the back. Yes, I know Scotty said in Balance of Terror: “Their power is simple impulse,” but that doesn’t mean the ship doesn’t have warp drive. In fact, it couldn’t make it from Romulus to the Federation border without warp drive. (it would take centuries) Also, in a scene cut from the episode, Cdr. Hansen of Earth Outpost 4 apparently commented on the Romulan ship’s similarities to a (Federation) Starship. He apparently went on to say that the Romulans must have had spies in the Federation to steal Starship secrets. So, it stands to reason that the things on the end of the wings that look like warp nacelles are in fact warp nacelles. Scotty may have meant the ship was flying at impulse, probably necessary to maintain its cloak. So, I put some simple impulse engines in the back, where a lot of people put them.