Shell mold casting is a metal casting process that uses a resin-coated sand mixture to form a thin-walled mold shell around a metal pattern. The pattern is heated and pressed into the sand-resin mixture to form the shell, which is then cured in an oven. Two shell halves are joined to form the complete shell mold, into which molten metal is poured to create the casting. This allows for high-precision casting of small to medium parts like gear housings, cylinder heads, and connecting rods. The shell mold casting process provides advantages over sand casting like better surface finish and dimensional accuracy for the final casting.