The push-pull between artistic inclinations and economic realities forms the backbone of A Rubberband Is an Unlikely Instrument, Matt Boyd’s protracted documentary about Walter and Andrea Baker, a largely nondescript middle-aged Brooklyn couple (with a young son) struggling to navigate personal and familial dilemmas. Walter is an aspiring musician and artist with an obsessive passion for Gibson guitars who refuses to fret about his family’s short- and long-term financial survival, a situation that increasingly comes to vex forward-thinking wife Andrea. Visits to Walter’s religious Texas family—from whom he’s long been estranged—create further friction, though of a mild sort that’s indicative of this torpid nonfiction feature. Director Boyd allows numerous scenes to run on far longer than necessary, and regularly inserts expressionistic shots of hands holding animals, sunlight peering through clouds, and barren roadways. Without any engaging small-scale human drama or larger social or culture-clash import, the film comes across as trivial, and too often also indulgent and pretentious. If nothing else, however, it does prove that when used for music, as it is by Walter in subway tunnels, a rubber band sounds eerily like a squeaky trumpet.