Abstract: An expanded, memory molded, increased density, highly impact-resistant polystyrene construct, and method of making the construct. The construct is formed by molding pre-expanded non-equilibrated polystyrene beads to a first volume, cooling rapidly, and then compression molding to a final, smaller volume. The resultant constructs have increased density, and high impact strength without increase in embrittlement. Also, the construct has "memory" in the sense that it returns substantially to its original shape after impact.