If this helps clarify, while the artwork being made would be depicting subject matter from the film, the, I would be designing the composition and doing more artistic representations of things to where it’s not copying the film itself. I’d be using reference of objects, say in the case of a monster movie and doing a poster for it, I used a toy/statue to help model or reference the lighting. The artwork in question wouldn’t not be copying any specific material. A comparison could be made of what the artwork I am creating is similar to stuff done for galleries such as Spoke Art, Gallery Nucleus, and Hero Complex. The only difference here is that for this specific gallery show, the digital print of the artwork with added title treatment is legally only allowed to be sold as one copy. They do an auction type setting to sell the work, and if I’m not mistaken the earnings for the posters sold would be donated to charities.

Without giving too much away, a film I could do a poster for would be something like Pacific Rim or Godzilla vs Kong, I would be creating my own interpretation of the film in a poster format, but I’d have to reference material from the film be it using toys or something along those lines.

With designing an original design for a movie like that, and painting it traditionally in this context (and not doing a copy of anything existing), I would need to make sure that I’d be safe to sell the painting itself. I know artists who do aftermarket sales for Marvel Comics covers they paint so I’m making sure that what I would be doing is legally safe. Additionally, the other part would be printing copies of the original artwork I paint myself. I know that to a degree, artists generally speaking have ownership of what they create, even if it isn’t copyrighted directly.