The improved mold assembly for cultured marble molding is provided. The mold assembly can comprise a male mold portion and a female mold portion. The assembly can further comprise a molding tool. The molding tool can have a side wall having an upper curved portion and a lower curved portion. The molding tool can have a bowl portion and an apron portion spaced from the bowl portion by a gap. The molding tool can be constructed from a flexible and/or soft material. The molding tool can facilitate molding of a countertop having at least one seamless curved edge and/or an at least partially seamless sink portion.