Styrene is polymerized with methyl methacrylate (PMMA) in different proportions, and then immersed in a foaming agent during polymerization to make an expandable copolymer resin. The proportion of methyl methacrylate involved in the polymerization of STMMA is high, and the beads contain 63% carbon.

STMMA-FD beads are a kind of resin in which methyl methacrylate is copolymerized with styrene in different proportions. The amount of methyl methacrylate involved in the polymerization of STMMA-FD is appropriate, and the beads contain 82% carbon. It can be more fully decomposed and highly gasified, with few solid residues, so it can be regarded as modified EPS.

Ceramic Sand is the custom ceramic particles with a spherical shape, high refractoriness and low thermal expansion being made by spraying the melted calcined bauxite. It provides a very simple but efficient way for the foundry-men to improving the quality of the castings, reducing the production cost and avoiding environmental pollution.