It’s a given that a fan film or fan fiction or fan art is borrowing from a property familiar to the artist. The results can be viewed as an homage or the lazy borrowing of another’s work, depending on the quality. The creator is trading originality for a built-in audience already invested in the subject matter. The greatest leeway is given when humor is introduced, as is the case with the cartoons, memes, and lampoons that fill sites like IMGUR and YouTube to the gills.
When a fan film elects to take itself seriously, though, it needs to deliver on multiple fronts to not be immediately dismissed and derided as a bad cover song performed by someone who can’t play their instrument.
An example of a fan piece that hits all the notes just right is the recent Hoshino directed by Stephen Vitale. It borrows a great deal, including the music, sound effects, costume design, and other trappings of the Star Wars universe. But this is part of the deal with fan work. The folks involved with the film’s creation are veterans of film and television. But Hoshino is still an example of getting the ingredients right and not resting on the fact that having enough Star Wars elements without a compelling story will result in a good product.
The film is short enough that I won’t detail the plot. Here’s a link:
Also worth watching is the brief making-of: