Abstract: A custom-fitting earplug (18) for hearing protection or other ear applications, or in-ear communications device mounting (40) is fabricated in situ by depositing a foaming material (14 or 24) within the person's ear (10 or 42, respectively) and allowing the foaming material (14 or 24) to expand therein to form foam (16 or 44, respectively). By applying slight pressure from outside the person's ear (10 or 42) through the stem (13) and/or keeper (11) during expansion, the foam (16 or 44, respectively) will be tightly packed in and conform to the ear canal. An optional sheath (15 or 36) positioned over the foaming material (14 or 24, respectively) serves to provide a smooth outer surface for the earplug (18) or communications device (40) produced and can aid in defining and limiting the expansion of the foam (14 or 24, respectively).