It’s a sort of hokey, 80’s premise that doesn’t necessarily blend well with the serious Primer-style depiction of a workshop tinkerer, but Atlas asks you to suspend disbelief and jump with him. Plausibility is not his goal, and he spends next to no time establishing behaviors or rules for this fantastic device. It could rub some viewers the wrong way, but I think it’s a perfect use of a cliché, as it exploits familiarity with the plot trope in order to progress the narrative, allowing Atlas to focus more on the story he wants to tell than the mechanics of it. It could be argued that tonally it is a clever move as well, that the use of a hokey setup establishes an audience expectation of the film that is eventually subverted, leaving the viewer more emotionally vulnerable to the eventual climax.