Robert Zemeckis has been known to take on a movie idea simply for the technical challenge it presents. Think of “Forrest Gump” inserted into history, “Polar Express” motion-capturing Tom Hanks, the dazzling starvation stunt of “Cast Away,” the You Will Believe Denzel can fly a jetliner stoned — and UPSIDE down — of “Flight.”

And he does his experimenting with a LOT of other people’s money — every project financed and scaled in blockbuster proportions. Nice work if you can get it.

Sometimes, of course, he lets the technology turn him into the cinema’s Tin Man. All he and his work lacks, in some of these projects, is a heart.

“Welcome to Marwen” allows Zemeckis and the best special effects minds in the movies to turn Steve Carell, Leslie Mann, Diane Kruger, Janelle Monaé and others into very human animated GI Joe and Barbie dolls.

But he brought in Caroline Thompson (“Edward Scissorhands,” “Black Beauty”) to co-script this story of a traumatized artist who self-medicates by acting out vengeance fantasies with dolls in an imaginary World War II combat zone — Marwen, Belgium. And Thompson, Carell and Mann give this exercise in CGI a sensitivity that makes it, if not a stunning success, then at least a fascinating failure — or near failure.

Carell plays Mark Hogancamp, a Navy vet and successful illustrator living in upstate New York, where guys with an artistic sensibility are bound to rub the rednecks the wrong way. Mark “had the memory beaten out of me,” his talent “ripped out of my brain” by five thugs outside the Avalanche Bar, a hate crime that nearly killed him, broke his spirit  and crippled his hands so that he’d never make a living drawing again.

But as he waits for the five to be sentenced for their crime, he gets back to creating. He buys dolls at the local hobby shop, where Roberta (Merritt Wever of “Nurse Jackie”) indulges Mark, nurtures him and is tuned in to what he’s doing with those dolls.

Mark gives them names and inserts him into the sets and dioramas he’s constructed in his yard and all through the mobile home where he lives. This is “the garden spot of Belgium,” Marwen, where his alter ego, Capt. Mark “Hogie” Hogancamp, was shot down during World War II, where he runs a local bar — The Ruined Stocking — as he keeps fighting the occupying Germans, who curse him in German every time they’re about to fill him full of lead.

“Sorry, I don’t speak Nazi, Captain!”

Whenever things get dicey for the outnumbered fighter pilot, a quintet of local women, habitues of his bar, show up packing grenades and machine guns, and mow the Nazis down. Because back then, America was unambiguous about Swastika-wearing thugs.

The Women of Marwen, “You dolls,” are his saviors, and Hogie dresses — and undresses them and poses them in provocative ways. Roberta and Caralala (Eiza Gonzalez), the cook he helps out at the local diner, are engrossed in the story — elaborate action/vengeance tableaux — Mark is telling with dolls who represent them, including his Russian caregiver and a couple of other women –his rehab coach (Monaé) — who have been in his life.

Roberta puts up with a lot in letting her doll-avatar take part in these battles for Marwen.

“What happened to my top?”

“It got ripped off!”

“AGAIN?!”

She sees the therapeutic value of this badly-damaged man’s doll posing. Others have seen the aesthetic appeal of Mark’s elaborate tableaux, covering dolls with blood staging atrocities, simulating wartime romance and then photographing the scenes. Those photographs have earned him an upcoming gallery showing.

If only they could be sure he’ll show up at the opening. If only his lawyer (Conrad Coates) can talk Mark into appearing in court so that his attackers get the punishment they deserve.

Leslie Mann plays Nicol, a compassionate veterinarian with her own damage who moves in across the street and finds herself in Mark’s Marwen saga and the object of his delusional romantic fantasies.

Carell is wonderfully subtle in this role, deftly handling Mark’s mania, his meltdowns and the swagger the real Mark cannot manage that his plastic-jointed doll alter ego, Captain Hogie, can.

Carell’s Mark is the very embodiment of a “town character,” timidly tugging a toy Jeep loaded with his Marwen Women everywhere he goes, wincing from blows delivered long ago and blows he fears are to come. It’s a funny performance, “broken” but touching. The trailers for the film suggest schmaltzy, but for me, “Marwen” never gets there.

Mann underplays Nicol as well, suggesting what drew the other supportive women who prop up Mark and figure as heroines in his World War II story to him. She is also the latest woman to ignore the “Don’t get close to Hogie” edict — out of pity, empathy and concern.

She is the audience’s surrogate, the new person to this world who gets Roberta to explain it to her and Mark to chronicle his pain, even though we’ve seen the scrapbook he keeps of newspaper accounts of his beating, graphic photos of his injuries and his scribbled comments in the margins.

“BROKEN.” “WORTHLESS.”

Because some of what’s going is him blaming himself for his injuries. Mark has a thing for women’s shoes, and not just the ones he poses on his dolls.

“They’re called ‘stilettos,” but they won’t be invented until 1954.”

Mark likes wearing women’s shoes. This wrinkle in the story is handled with more sensitivity and less sensationalism than it was in the 2010 documentary “Marwencol,” about Hogancamp’s life and art. The women of Marwen understand it, especially the new woman in town, Nicol. Anybody who has ever lived in a small town will find that a bit of a head-snapper.

But that’s a big theme of the Thompson and Zemeckis script — that “different” is nothing to be ashamed of, that there is no guilt in a little harmless shoe fetish. That’s Mark’s journey, learning that and facing the demons of intolerance who beat him and left him to die.

The knocks against “Welcome to Marwen” begin with the glib pop psychology practiced here and continue through some fairly shameless manipulation. There is no more ham-fisted filmmaker working than Zemeckis when it comes to unnecessarily underlining every BIG MOMENT with a piece of pop music so on-the-nose as to be redundant.

Mark and Hogie’s relationship to the Marwen witch (Diane Kruger, in doll form) is set to a cover of “Spooky,” Patsy Cline’s “Crazy” pops up — as if we can’t figure out Mark’s diagnosis for ourselves. The leggy, Barbie-thin avenging angels of Marwen march up to the Nazis — in stilettos — to the tune of Robert Palmer’s “Addicted to Love.” An abusive bully in Nicol’s life (Neil Jackson, scary good) is a big Ted Nugent fan.

Zemeckis has been doing that since “Forrest Gump,” and I just wish one studio exec would tell him, “No more music clearance money for you, pal. Enough already.” It’s a ridiculous crutch.

Those failings can take one right out of the movie, but they don’t ruin it. Carell and Mann create characters we care for, fear for, and root for even if we know there’s no realistic or practical connection between them. Zemeckis makes Hogancamp’s loosening grasp of the difference between his reality and the real world’s version harrowing and eye-popping.

“Welcome to Marwen” won’t be another Zemeckis blockbuster, won’t be anybody’s idea of Oscar bait. But here’s a thought-provoking holiday movie that gives the viewer something to chew on even if the story feels a trifle undigested, at times.

MPAA Rating: PG-13 for sequences of fantasy violence, some disturbing images, brief suggestive content, thematic material and language

Cast: Steve Carell, Leslie Mann, Janelle Monae, Diane Kruger, Siobhan Williams, Eiza Gonzalez

Credits: Directed by Robert Zemeckis, script by Caroline Thompson and Robert Zemeckis.  A Universal release.

Running time: 1:56