Abstract: An improved process for making a vent for an "in the ear" hearing aid. A cavity is formed which corresponds to the structure of the ear canal and outer ear of the hearing aid user. A molding liquid, such as acrylic, is poured into the cavity. The liquid is allowed to partially cure and form a thin-walled shell inside the cavity. An elongated mandrel is then placed along the inside of the thin-walled shell, and additional liquid molding material is poured into the thin-walled shell around the elongated mandrel. The wall of the shell accordingly becomes thicker, enveloping the mandrel. The mandrel may then be removed, leaving the vent in the wall of the shell.