Film Riot is a web series that exists to help low-budget filmmakers add special effects to their films. While most of what they cover is digitally based, they featured an episode that showed how to use a miniature in combination with digital tools to get a very nice result. The principles will be familiar to anyone with an interest in miniatures in film, but the practice of using off-the-shelf models and toys for a miniature is one that even the pros have turned to on occasion (and that we have touched on here.)
Of course, I would encourage filmmakers to resist the urge to put a helicopter in your film just because you can. One of the reasons the early Star Wars films were so successful was because the miniatures were not showcased - they were merely a means to advance the story.
Film Riot: Put a Helicopter in Your Film!