Custom in-ear monitors (headsets, headphones, earbuds, hearing aids) having improved audio fidelity characteristics and improved manufacturability are constructed by designing a virtual three-dimensional model housing including sound and vent tubes, and equipment mounting receptacles and clips; and fabricating the housing substantially simultaneously or all-in-one-go using, e.g., a 3D printer. The sound and vent tubes comprise features such as inflection points and profile variations that are impossible to construct using traditional subtractive manufacturing processes.