A mold-making device may include a stirring device including a stirring tank and at least one stirring blade. The stirring device may further include a packing port that is configured to open and close on a bottom of the stirring tank. The stirring device may stir a particulate aggregate and at least one additive by rotating the at least one stirring blade within the stirring tank to yield an admixture. A forming mold may communicate with the packing port and mold the admixture into a predetermined shape. A packing device may compress a surface of the admixture within the stirring tank and pack the admixture into the forming mold via the packing port.