I came across an interesting post about John Williams. You know, the guy who wrote the music for Star Wars, Harry Potter, and countless other films.
He was talking about his non-film projects. His pieces intended for the concert stage. Pieces one might actually study at a conservatory.
He said that he considers these pieces "self-education."
As an example, he wrote a harp sonata. He explained that one needs to become extraordinarily harp-savvy in order to write a piece like this.
This is a challenge every composer faces - learning to write properly for every instrument. And what an interesting way this is to tackle it.
After writing a harp sonata, our friend John can take the skills gained from that and apply it to every harp part for every film score he creates for the rest of his life.
So...what's a skill that would be helpful in your work that you could create a project out of?