Llyn Foulkes is one of American art's true originals, at times curmudgeonly, at others self-doubting, but always forthright and often controversial. He puts his quirks on display along with his talents in a new documentary opening today in New York. Llyn Foulkes: One Man Band chronicles seven recent years in the life of the persistently unhappy 79-year-old Los Angeles-based painter and musician. After early triumphs followed by decades of relative obscurity, Foulkes has enjoyed renewed attention lately, including a well-received traveling career retrospective.

Foulkes appeared on the L.A. art scene in the 1960s, along with John Baldessari, Robert Irwin and Ed Ruscha, although he did not achieve the sustained commercial and critical successes of his peers. In 1961, he joined and was swiftly kicked out of Ferus Gallery, the well-known L.A. incubator of young talent. The reason for his expulsion is unclear, but it had something to do with interpersonal conflict and Foulkes's open distaste for other artists' work. "I didn't go to their parties," Foulkes says in the film. He had post-Ferus solo shows at two California museums and won an important prize at the 1967 Paris Biennale. Since then, he has worked steadily, if inconsistently, in various genres including landscape painting, assemblage and portraiture, despite limited reviews and sales. The artist is currently represented by Kent Fine Art in New York.

Foulkes also has a music career, including a 1974 appearance, with his band, on "The Tonight Show With Johnny Carson." The band broke up after Foulkes fought with the female lead singer. Since then, he has performed solo on a self-built, Dr. Seuss-like assemblage of instruments he calls "The Machine." His music provides the film's soundtrack.

In the 90-minute documentary, Foulkes seems an uncompromising, at times angry but nonetheless tireless talent with tendencies toward self-sabotage, perfectionism and hermeticism. Throughout the film he continually reworks, by hand, hammer, saw, machete, paint, sander and brush, two large and ambitious three-dimensional paintings. One of them, The Lost Frontier (1997-2005), received scant attention when it was shown at a New York gallery, and the film documents Foulke's enormous disappointment with that showing. Just before the movie wrapped, however, the piece was purchased by Los Angeles's Hammer Museum.

The other work featured in the film, The Awakening (1994-2012), depicts a spooky version of the artist sitting up in bed with his second wife. Over the course of 18 years, Foulkes painstakingly reduced the 10-by-14-foot work to its final size of around 3 by 4 feet. After repeatedly insisting that it was not finished, he sold it to the actor Brad Pitt just months after the film's conclusion, according to the film's producers.

Produced and directed by Tamar Halpern and Chris Quilty, the movie incorporates interviews with 20th-century L.A. art-world regulars like Dennis Hopper and George Herms, as well as insights from curators, gallerists and Foulkes's ex-wives. Throughout, Foulkes speaks candidly and unguardedly, particularly when he's railing against "corporate" art and the insidious nature of commercial pop culture, especially, but not exclusively, Disney products.

Unlike most other artists of his stature, Foulkes works without studio assistants. "I feel like I'm a one-man band in art and in music," he says, "and it's very discouraging."