For many casual fans of music, there can be a rigidity to the ways in which a musician is allowed to express themselves. Without necessarily being conscious of it, the listener will pay deference to tradition and professionalism: music is made by guitars, drums and pianos, that look demonstrably how we expect them to look. I remember first seeing Tom Waits perform with his menagerie of homemade instruments -- gnarled totems assembled from junkyard detritus, emanating sounds just as wonky as their appearances, in service of a madman's vision of music -- and having my expectations of homogeneity challenged. In Waits' eyes, a guitar made from a cigar box or a saxophone built from PVC pipes more closely approaches a feeling of no-frills musical purity.

Minnesota-based artist Paul Metzger is also fascinated with building mad musical machines. His primary instrument is a mutated banjo, now affixed with 23 strings, 13 of them being sympathetic ones that hum in support of the rest of the strings. In this way, Metzger's creation is now more similar to a sitar or a sarod than it is a traditional banjo; rather than plucking it, Metzger will frequently let it drone with the aid of a bow. Here, and in every other aspect of his art, Metzger has absolutely no qualms about starting from scratch, restructuring and reinventing as he goes along. One of his other contraptions is an unwieldy Frankenstein's monster made out of the guts of more than a dozen music boxes.

Part of Metzger's willingness to approach music from unusual angles is surely due to his status as a self-taught musician. His performances being largely improvised means that he is able to create and compose through intuition and feel, having no greater goal than to find previously unheard sounds. Metzger's music is about accessing a mood and stretching it out into something surprising and transportive. His most recent release, Uses of Infinity, is a six-part suite that was recorded in a single take in a de-sanctified cathedral, and the range of tones and droning textures that he coaxes out of that 23-string banjo is astonishing. Vacillating from the serenely meditative to the prickly and unsettling, Uses of Infinity stands in defiance to genre or categorization.

What Metzger creates, though resolutely avant-garde, is still eminently approachable. In interviews, Metzger talks about how one of his greatest joys is to make instruments for friends, regardless of their musical prowess, and this penchant for inclusivity bleeds into his music. While some may be trained to hear experimental music as a provocation, a barrier to the hoi polloi, Metzger's music excitedly invites the listener to follow along on a journey of discovery. The formally untrained musician is just as interested as you might be in wondering where he'll go next, which lends his performances an innate fascination for all involved.

In wiping your mind clean of expectations for what instruments are meant to be and how music is required to sound, you wind up with a more enriching experience for performer and audience alike, which may be the most valuable service that Metzger provides. There's a childlike enthusiasm for experimentation that exists, exuberantly alive, in Metzger's music. It doesn't hurt that his homemade noisemakers are often such beautifully ragged objects to behold -- a violin made out of gourds, a fundamental subversion of music boxes, a humble banjo given a new life in homage to classical Indian instruments. Metzger's music becomes almost a performance art piece, playfully deconstructing tradition and digging deep into the dirt to construct something new, compelling and thrillingly vital.

Paul Metzger, w/ Liquid Letters, John St. Pelvyn, 8 p.m., Wednesday, Oct. 11, $5-$10 suggested donation, Dub Narcotic Studio, 802 Jefferson St. SE, Olympia