For Jeremy Harris, making music involves more than just inspiration: it requires discipline. “It’s really easy to have an idea,” he said, “but to follow through and put all the hard work in is the task.”

It is that approach with which Mr. Harris, 27, has strung together a career of performing in bands across the Bay Area and composing scores for television commercials and other musicians. And it is what led him to his latest project, a film score involving an ensemble of classical and folk instruments that is now coming to life in his Inverness home.

Written for more than two dozen instruments, ranging from brass and woodwinds to banjos and what is known as a musical saw, the score will accompany a 10-minute animated film, directed by a group of filmmakers with whom Mr. Harris lived in the mountains of Santa Cruz.

It has drawn participation from students from a San Francisco music school, whose visits to his home over the past month for recording purposes are the final stage of a process to which Mr. Harris has dedicated much of the past year.

And it marks the biggest step in a career that came into focus six years ago, when Mr. Harris booked a flight on a “gut instinct” to San Francisco, where he said he “met some of my closest friends within the first 48 hours.”

“As soon as I showed up, things started clicking into place,” said Mr. Harris, who sublet a room in the Inner Sunset district for three months, during which he joined a few bands (with whom he still performs(, before returning to Berklee College of Music in Boston, Mass., where he studied classical music.

After graduating, he headed back West, this time for Los Angeles. That was where he nearly took a job producing scores for Paramount Pictures. But his intuition—and a fear of becoming “one droplet in an ocean of composers”—led him back to the Bay Area.

There, he eventually met the group of directors behind a film called The Tale of Hillbelly, whose storyline involves a yoga instructor who has a life-changing encounter with a fox while hiking in the mountains.

But the outcome of the film was, from the very beginning, clouded with doubt. “We were just kind of going on faith,” Mr. Harris said of the crew, which was struggling to come up with enough money to pay for recording costs and other expenses. “We didn’t know how we were going to hire people [to play the 30 instruments involved in the score].”

That uncertainty subsided when the crew received a grant for tens of thousands of dollars from a visual arts fund overseen by the Community Foundation of Santa Cruz County. The extra financial support helped Mr. Harris draw involvement from students of the San Francisco Conservatory of Music, who for the past month have trickled in and out of his home, recording parts of a score Mr. Harris expects to finish before the film is released in May or June.

The recordings, sometimes lasting late into the night, do not bother his housemate and partner, Asia Wong, a vocalist and dancer with whom Mr. Harris recently moved from Petaluma to Inverness.

The two, supportive of each other’s pursuits, have since made tentative plans, including running an gallery in their home and creating a map of music scores derived from their hiking trips across Point Reyes, in an area they have grown to admire. “I feel like a lifer around here,” Mr. Harris said in the Blackbird one recent weekend. “We both do,” Asia added.