An apparatus for manufacturing simulated stone products is provided. The apparatus includes a mold having mold cavities. The mold cavities have a first section and a second section that intersect to form a cavity angle. A hopper is configured to introduce castable material into the mold. The hopper and the mold are moveable with respect to each other, enabling them to be selectively engaged with each other. The hopper includes a first funnel wall configured to contact the top of the first mold cavity and to introduce castable material into the top opening of the first section. The hopper has a second funnel wall configured to contact the second section and act as a barrier to close the top opening of the second section of the mold cavity.