Abstract: A seamless self-insulated foam duct made from a single continuous homogenous member of polymeric foam and an apparatus and methods for making such ducts. The homogenous foam member may be transformed to include a plurality of layers such as a densified inner foam layer surrounded by an outer insulating foam layer. The outer insulating foam layer may be partially densified to form a densified outer foam layer. In one embodiment the foam member may be wrapped and bonded to an external layer coating that provides additional protection to the duct. In one embodiment the foam duct is modified to have nestable ends whereby one end of a first foam duct is sized and shape to fit within and snugly engage a compatible end of a second foam duct. The duct may be manufactured by an apparatus capable of implementing a series of cutting and densifying steps that result in custom-sized foam ducts having one or more densified foam layers.