Abstract: A loose packing material for the muffler of an internal combustion engine is confined by a mesh, for handling the loose packing as a unit during assembly of the muffler. The openwork nature of the mesh is such that the mesh does not affect the sound or tune of the muffler, such that the original sound of the muffler is the same as its long term sound. The mesh can comprise fiberglass or metal mesh, but preferably includes a heat consumable material such as a thermoplastic polymer. The mesh can be formed as a wholly or partly closed bag with a shape complementary to a muffler cavity, which can be irregular. The heat consumable type of bag is formed by heat sealed seams. The mesh holds the loose packing material clear of peripheral seams or internal points at which structural parts of the muffler are intended to abut. The confined packing and its methods are particularly apt for stamped plate mufflers and are likewise applicable to other forms such as rolled casing and extruded casing muffler structures.