Abstract: A system includes a first scanner having an inflatable membrane configured to be inflated with a medium to conform an exterior surface of the inflatable membrane to an interior shape of a cavity. The medium attenuates, at first rate per unit length, light having a first optical wavelength, and attenuates, at a second rate per unit length, light having a second optical wavelength. An emitter is configured to generate light to illuminate the interior surface and a detector is configured to receive light from the interior surface. The scanner further includes a processor configured to generate a first electronic representation of the interior shape based on the light. A design computer is configured to modify the first electronic representation into a three-dimensional shape corresponding to at least a portion of the interior shape and a fabricator configured to fabricate, based at least on the modified first electronic representation, an earbud.