Abstract: A plastic or elastomeric foam cavity filler, useable for filling of cavities such as are found in vehicles, ships, boats, mobile or modular homes, buildings, machinery, and equipment comprises a flexible pouch containing at least one material suitable for chemical or thermal activation which, upon activation of the material, the flexible pouch is placed in a cavity. The material expands the pouch to fit the cavity in which it was placed, restricting the entrance of, or transmission through, of noise, vibration, or fumes. When more than one foam component material is used, the component materials are separated within the flexible pouch. Among the means of separation are a pouch within the flexible pouch or barriers forming separate compartments in the pouch.