Shane Carruth, a young Dallasite, essentially taught himself filmmaking by reading, watching movies, experimenting with equipment and asking questions of professionals willing to talk to him. Now his debut feature, “Primer,” an intricate puzzler involving two young engineers who invent a time-travel device and made on a ultra-shoestring budget (reportedly $7,000), is opening in theatres after winning the Grand Jury Prize at this year’s Sundance Festival. In a recent interview Carruth discussed writing and directing the picture, as well as starring in and editing it and experiencing the award-winning premiere in Utah.

“Thematically,” Carruth said of the genesis of the script, “before I knew it had anything to do with science or science fiction…I was just interested in a story where you’ve got these two guys at the beginning of the story that have a pretty conventional relationship and the ability to trust one another, and because of the introduction of this device or this power in changing what’s at risk, it makes it so they’re not even able to be around each other at the end of it, not because anyone’s a good or bad person, it’s too much to trust with another person. The idea of finding yourself in someone else’s past and questioning how much control you have over the events around you, to me that’s something at risk that’s worse than any kind of physical harm, and so a lot of the reading I was doing about innovation…led me to setting up the premise….This ability to affect time, that’s what satisfied the equation thematically for me. It did seem like there were a lot of interesting things to do with it that I hadn’t seen before….The idea is that they don’t have to worry about the same paradoxes or causality problems that you get in ‘Bill and Ted’ or ‘Back to the Future.’ The story kind of assumes that they’ve seen those movies,” Carruth added to general laughter.

He continued: “Then it was a matter of, how do I make this plausible, how did I believe that this device would occur in the world? To be honest, at that point it gets really fuzzy, because it’s not a direct line into ‘Okay, let’s research superconductors.’ At some point I probably realized that if we’re going to say that we’re affecting time, then let’s talk about affecting space and time, so I’ve got to start with something that’s affecting gravity, and that leads to diamagnetism. And that’s when I did research on superconductors. And basically everything in the film, up until the point where we say it’s affecting time, that’s all based on real stuff–this idea of using superconductors to exhibit diamagnetism in objects that aren’t magnetic or metallic, that’s real stuff. It just usually requires a machine the size of a house that’s cooled to near absolute zero. So our guys are finding ways around that and tweaking other devices to make that happen. But everything up until that point, it’s all based on real stuff.”

Knowing that he’d be shooting on a tiny budget affected the script, too. “When I was writing it,” Carruth said, “I wrote for locations I knew I had access to. But I think in knowing that, I wanted to do that story. This isn’t going to be a story about a government project built into the side of a mountain. I can’t do that story. So knowing that it’s going to come out of someone’s garage and it’s going to involve a small number of characters, I don’t know if I reached the point where I said, ‘Oh, it has to be this,’ so then I just tried to find an interesting way to do that, or it was the other way around, because to be honest, I think it’s much more interesting that way–if it becomes this intimate thing that only two people know about, because the whole idea of it being proprietary, that [when] they find out that this thing does something fantastical, the first thing they do is cut out the other two guys. So I think maybe I lucked out…but I ended up with a story that actually fit the budget.”

At first, Carruth had no intention of playing one of the two major parts. “I had tried out over a hundred guys for the lead roles,” he explained. “I had a pretty specific idea about how I wanted the acting to be, that I wanted it to be as real as possible, and [that] the drama needed to come out of this story and the revelation of parts of the plot, as opposed to a performance. I wanted to believe every moment of it, so that when we do get to these fantastical things, hopefully it’s already set in such an almost realistic world, you buy it and make those leaps with the story. So because of that, and because I wasn’t offering to pay anybody, the casting calls didn’t go so well. I was able to find David Sullivan [the other lead] out of that process, but it was a pretty bad thing. So at one point I realized that I had memorized a good portion of the script, just trying to show by example what I was looking for, and since I was roughly the right age, I just decided that’s one less person I would have to call every day, and I know I’m going to be there….Looking back on it, since I hadn’t directed before, I think it was a good thing to be in the scenes, because I was feeling what the other actors were going through–‘Does this feel false? What’s wrong with it? What’s really going on?’ As we were rehearsing, I think you get a better perspective than you might from standing on the sidelines.”

The actual filming was only a small part of the work involved in making the film. “It took five weeks to shoot,” Carruth said, “and then it was about two years of editing and foleying and dubbing and stuff. And that was, for the most part, me in my apartment, alone, so this film was this thing that was four inches wide on my monitor.” That explains why finally seeing the finished product at Sundance with an audience was such a shock. “Suddenly I’m sitting with hundreds of other people, and it’s twenty feet high. And for the first part–you know, it’s not a comedy, but there are little bits of humor in it that I had completely forgotten about until I heard people laughing.” Seeing himself on the screen wasn’t so shocking, though. “I’ve looked at that footage so much…that I don’t even see myself anymore. It seems it’s just like somebody else, some actor that I’ve got to fix in the editing room, basically…not as bad as it was when I first saw the footage.”

What really astonished Carruth was when “Primer” was announced as the Sundance winner . “Finding out that it won the jury prize, I was in complete shock…The thing is that as people were winning that night, they would go up on stage and they had a list of people to thank, and they were eloquent…and I was certain that they knew ahead of time. I thought someone had pulled them aside a couple of hours before the ceremony and told them…and I was so certain of that, that I was just enjoying the show. And Danny Glover comes out on stage…he’s a celebrity, and we’re just enjoying him talking, and he says the word ‘Primer,’ and I don’t remember a lot after that. I remember standing in front of the mike…and I don’t have a word in my head to say.”

The question now for ThinkFilm, which picked up the picture for distribution at Sundance, is whether the intricacy of “Primer” will sit well with audiences. “It’s so pretentious to say that my favorite films in the world are the ones where I walk away from them and I feel like I’ve seen a story, but if I take another look I realize there was more information in there,” Carruth said. “And my intention was not to have a convoluted plot, but one that isn’t summed up or tidily explained, but to make sure the information is in there. However, the first time you see it, it’s an enjoyable experience, and if you decide you want to see it again, there is more to see. Having said that, people have come up to me after they’ve seen it twice and the second time seems to be a much different experience. Even as I was editing, I made sure that the information is in there. The first time, to be honest, I hope it’s an enjoyable experience, but I don’t think there probably is a way to get everything that’s going on, but I hope that doesn’t affect whether it’s enjoyable or not… Usually a second time, people walk away with much closer to a hundred percent of what’s going on.”

So you just might want to buy two tickets to begin with.