An in-situ molded foam core structural plastic article having an outer shell with an interior cavity filled with expandable polymer beads which when expanded substantially fill the interior cavity forming a thermal bond with the shell. The bead and shell are of a similar plastic composition enabling the articles to be reground and recycled. Various articles are disclosed including structural panels, and automotive seat, load floor, interior panel, bumper and running board components. An apparatus for forming the articles and an associated method of manufacture are also disclosed.