When the studios started re-testing the 3D waters a few years ago, naysayers pooh-poohed the potential impact of stereo on the box office. But films from “Avatar” to “Thor” proved them wrong, and 3D has taken on the aura of tentpole-maker.

Now, with the cost of 3D production and post-production tools falling rapidly, several lower-budget projects are gravitating to the stereo medium, attracted not only by its ability to heighten B.O. coin but also by the creative possibilities.

These projects range from those of European and Japanese auteurs to pics by indie filmmakers, with titles ranging from documentaries to horror films.

Werner Herzog’s “Cave of Forgotten Dreams” takes viewers on a journey deep into the Chauvet Cave in France, which holds some of the most ancient visual art made by humans. Wim Wenders’ documentary “Pina,” a film about the life and work of dancer Pina Bausch, wowed auds at the Berlin Film Festival and will soon be in theaters. Japanese filmmaker Takashi Miike will show his 3D drama “Hara-kiri: Death of a Samurai” at Cannes.

On the Croisette, indie buyers have a chance to view around 50 stereoscopic 3D screenings — a 50% rise over last year — while organizers have added four more 3D-equipped screens, for a total of 14 out of 34 screens.

Closer to home, indie drama “Deep Gold 3D,” horror film “Julia X 3D” and mid-budget adventure story “Sanctum” have been among the pics to benefit from manageable 3D production costs, as well as an increased audience interest in 3D — and exhibitors looking satisfy those auds.

“In our case, it felt like 3D would take our story to the next level,” says P.J. Pettiette, “Julia X 3D” helmer. “When we started thinking about 3D, we realized it would open up new ways to put the audience in the middle of the horror.”

Pettiette, who’s planning a 3D Western, says the format is a good fit with certain genres, especially horror and adventure, and gives indie filmmakers a way to capture the attention of distribs and exhibs.

“For me, (3D) brings back the excitement of discovery in making movies,” Pettiette says.

Michael Gleissner, who produced, directed and wrote “Deep Gold” found doors opening once he had a 3D project to offer exhibs.

Gleissner hadn’t planned to use the format, since the cameras can be difficult and expensive to manage, but when Asia-based Digital Magic worked with him on tests, he realized a good-looking conversion was affordable even on his micro budget. Neither Gleissner nor Digital Magic would provide figures.

Though it might seem like 3D makes certain films a slam dunk at the box office, “Sanctum” producer Ben Browning, who worked on the adventure pic with exec producer James Cameron, cautions that the process must be part of an overall strategy that fits the story and the marketplace.

“With ‘Sanctum’ we had an advantage, because James Cameron’s name gets people interested in a movie,” Browning says. “But this still had to be a story where 3D made sense, and we still had to be mindful that we didn’t have the same budget as ‘Avatar,’ and we had to be smart about the timing of the release.”

Browning says a 3D indie needs to enter the market when there isn’t a lot of competition for 3D screens, because tentpole releases will push such films right out of theaters. He adds that 3D should merely enhance a strong story, and that a film must be good enough to play in both 3D and 2D to be profitable.

“Even though you have a lot of people who love 3D, you still have to be out there in 2D,” Browning says. “There are a lot of 3D screens, but the competition for that real estate is fierce.”

Films that come out in 3D — indies included — can also look to benefit from the increase in sales of 3D TVs. Since a large chunk of indie film viewing is done via VOD or traditional disc rental, more 3D screens in the home translates to more viewers looking for such titles.

Jonathan Sehring, whose IFC picked up Herzog’s docu, says while the pic’s 3D aspect wasn’t paramount in its decision to buy the film, it was certainly something the IFC prexy felt could be used as a selling point.

“When we got interested in ‘Cave of Forgotten Dreams’ it was because it was a great movie,” Sehring says. “But we’re also interested in being out there in front of new technology and what our viewers want to be able to see in the theaters and at home, so it does make a project more interesting to us.”