Here are some images of AMT's 1/537 scale Romulan Bird of Prey from the Star Trek TOS episode "Balance of Terror".
The one big inaccuracy I have noticed about this kit is that the front leading edge of the main body section should have an inward angle similar to that of the saucer section on the Enterprise. They have corrected the bussard collectors and added a plasma launcher which was not available in the original kit from the 70's making it more accurate to the original.
I am led to understand that the original Romulan Bird of Prey was destroyed in a fire during the series production. This is perhaps why one sees Klingon D7's in the later Star Trek episode "The Enterprise incident".
The Bird of Prey was a variety of Romulan warship in use during the 2260s (not to be confused with the Klingon platform also known as the Bird of Prey). Ships of this class were built as a saucer-shaped primary hull with two nacelles attached by forward-angled pylons. The most distinctive feature, however, was a red and white bird in flight painted onto the bottom of the hull. According to background lore, the original script for the episode "Balance of Terror" called for the Romulans to have a ship that was a copy of the USS Enterprise, which the Romulans had built using Federation technology that they obtained through espionage. However, the producers ultimately decided to have the Romulan ship only vaguely resemble the Enterprise, as evidenced by the saucer-like hull and pylon-mounted cylindrical nacelles.
In the episode "Balance of Terror", one such vessel crossed the Romulan Neutral Zone, destroyed three outpost satellites, and retreated in order to test Federation resolve; however, the Bird of Prey was heavily damaged by the USS Enterprise before it reached Romulan space, forcing its commander to scuttle in order to avoid capture.
Birds of Prey had advanced weapons compared to Starfleet ships of the period, featuring a cloaking device and powerful plasmatorpedo launcher. However, the ships were slower than Federation craft due to a more primitive warp design. This ship also seemed to suffer from an acute fuel shortage in the episode, which implies limited range, and also more of a Federation-style fusion or antimatter-based drive system as opposed to the artificial quantum singularity power sources of the later Romulan ships in Star Trek: The Next Generation.
In "Balance of Terror", when asked for an estimation on the power limitations of the Romulan ship, Scotty responded that "Its power is simple impulse". Because impulse power is commonly associated with sublight speed, this line had, at one time, been interpreted by many including the Star Fleet Battles gaming universe to mean that this type of ship and those before it lacked warp drive and that warp technology was gained from their alliance with the Klingons. This supposition is not supported on screen or in Star Trek: Enterprise episodes involving Romulans. In later editions, the "impulse only" statement was reinterpreted to indicate that the Romulans at this time only lacked tactical warp capability, meaning that they were unable to engage in combat at warp speeds and were required by power limitations to slow to sublight in order to fight.
"Balance of Terror", written by Paul Schneider and directed by Vincent McEveety, is a first-season episode of the original Star Trek series that first aired on December 15, 1966. The episode is a science-fiction version of a submarine film; writer Paul Schneider drew on the films Run Silent, Run Deep and The Enemy Below, casting the Enterprise as a surface vessel and the Romulan vessel as a submarine.
This episode introduces the Romulans. Additionally, Mark Lenard, playing the Romulan commander, makes his first Star Trek appearance. Lenard later played Spock's Vulcan father, Sarek, in several episodes and movies, and appears as the Klingon commander in Star Trek: The Motion Picture. These roles made Lenard the first actor to play characters of three prominent Star Trek races.