This application relates to methods and apparatus for waterproofing an electronic device having an audio output. More particularly a method for dynamically forming an acoustic volume of air for a speaker component is disclosed. The dynamically formed acoustic volume creates a sealed volume of air that prevents moisture from entering a portion of the device that includes moisture sensitive components. By dynamically forming the acoustic volume during a blow forming operation, the acoustic volume can utilize unused space within the electronic device in a highly efficient manner by occupying small areas of unused space that would otherwise go unused.