One or more fly ash materials or other optimized mineral fillers having a particle size distribution that may include cinders of selected sizes is mixed to form a filler. The filler is then mixed with an acid scavenger, an antioxidant, a compatibilizer and an impact modifier into a resin to form either a final composition or a masterbatch. A blowing agent may be added to both. Either the masterbatch or the final composition is mixed with a blend of a mineral oil and a styrenic block copolymer. Thereafter the masterbatch if prepared is mixed into or with a base resin to form the final composition. Fractional melt may be used in the masterbatch and in the final composition. The physical properties of the resulting products can be controlled by varying the ingredients. Some masterbatches are combined to produce products that have improved impact strength and/or that have enhanced toughness when compared to products made using naked or virgin resins. Alternately, the blowing agent may be added just before processing the composition into a final product.