3D movie trailers are usually composed of scenes from the movie, but they do not necessarily appear in the same order as they appear in the film. This is done to avoid giving spoilers. The scene to be selected is the funniest, most interesting or the most emotional, anything that can catch the attention of viewers. Initially, the trailer shown at the end of the film, thus the term, but this was later changed since moviegoers usually leaving the cinema at the end. Trailers are now shown before the movie starts. You can know more about 3D trailers via https://fanfestworld.com/category/trailers/.
The parts of a trailer for a regular movie and a 3D movie is basically the same. Here are some parts of the 3D movie trailers.
Voice-over is a useful tool to increase understanding of the movie audience. This comment is needed that scene alone can not provide.
Music helps in setting the mood of the trailer / movie. It is carefully selected by the crew and filmmakers. Music can of popular songs or of songs specially composed for the film. In the last part of the trailer where the most emotional scenes that appear, music plays a very important role.