There is something fascinating about art, especially popular art, that never completely makes it out of the gate, about movies or albums that remain unmade, unreleased or somehow incomplete.

Think of The Beach Boys "Smile," for example (and no, the 21st century version doesn’t count).

Or Orson Welles lost, original cut of "The Magnificent Ambersons." Or The Clash’s "Rat Patrol from Fort Bragg," the double-album that was eventually trimmed to become "Combat Rock." Or Erich von Stroheim’s nearly-eight hour cut of "Greed."

Heck, novelist Lewis Shiner wrote a terrific book called "Glimpses" all about the lure of unmade albums.

The mother of all unmade movies might be legendarily psychedelic Chilean director Alejandro Jodorowsky’s attempt to make "Dune."

Frank Pavich’s excellent documentary "Jodorowsky’s Dune" (which won the audience award at this year’s Fantastic Fest) is the story of that attempt, of Jodo’s trippy vision for the movie, of the talent he assembled, of his pure ambition for the thing.

As one talking head notes, what if Dune, and not Star Wars, had been the first modern special-effects-laden sci-fi blockbuster of its kind released?

From the jump, Jodorowsky, coming off the cult success of "El Topo" and "the Holy Mountain," had grand plans, probably too grand. Thinking himself a "spiritual warrior" for this film, he surrounded himself with sharp collaborators.

Teamed with Parisian producer Michel Seydoux, brilliant French cartoonist Jean "Moebius" Giraud, Swiss surrealist H. R. Giger and English sci-fi artist Chris Foss, Jodorowsky wanted to make the ultimate psychedelic, spiritual sci-fi epic.

(This just in: H.R. Giger, who became galactically famous a few years later for designing the genuinely-disturbing creature from "Alien," has the perfect speaking voice for H.R. Giger: scratchy, slightly high and inadvertently completely evil-sounding).

Pavich talks to most of the key players (Moebius and effects artists/future "Alien" screenwriter Dan O’Bannon are dead, sadly). He also lets us see some fantastic storyboards and animates key sequences. That alone will be worth the price of admission for "Dune" nerds.

Jodorowsky put his son Brontis, now 51, through two years of martial arts training to play Paul Atreides. Jodo senior wanted David Carradine for Duke Leto, Mick Jagger for Feyd-Rautha and Orson Welles for the obese Baron Harkonnen.

He wanted Pink Floyd to do the good guy music and French prog rock band Magma to do the bad guy music. No thinking small for this guy (and yes, the ending Jodorowsky came up with is far, far more bonkers than that the corny David Lynch movie; textual fealty was not part of the plan).

The now-84 year old director is still animated and still deeply charismatic. That goes a long way to mitigating the inherent goofiness in declaring he wanted this film to be "the most important picture in the history of humanity."

Somehow that comment is not nearly as annoying as "Drive" director Nicolas Winding Refn declaring that Hollywood was "afraid" of Dune. Afraid of losing their shirts on a movie that could have run 12 hours? Possibly. Afraid of Jodorowsky’s vision? Come on, man.

After two years of pre-production, the director couldn’t get the funding together and the plug was pulled. Ideas from Moebius’s storyboards and character designs ended up is a series of utterly bonkers comic books Jodorowsky wrote with Moebius and other artists.

Parts of the unmade film ended up, directly or indirectly, everywhere from "Flash Gordon" to "Alien" to "Prometheus" to, yes, "Star Wars."

The truth is that Jodorowsky’s vision of Dune still exists from whence it sprang: the realm of dreams, where it can still be perfect and mind-blowing.