This is a vintage Byron Molds complete "Baby Doll" B 112 ceramic slip casting mold.  The head mold (mold A) 7-in long by 7-in wide by 6.5-in tall, the body mold (mold B) 9-in long by 6-in wide by 7-in tall, the leg mold (mold C) is 9.5-in long by 9-in wide by 5-in tall, and the arm mold (mold D) 8.5-in long by 7.5-in wide by 4.5-in tall.  It may need a quick cleaning before use.  If you have any questions let me know.