Abstract: A plurality of identical green sand molds are sequentially formed by horizontal compaction on automatic mold making machinery. Each mold has a front and back vertical face with a recess formed in the front face and a plurality of down runners formed in the back face. A mold piece insert is formed of a mixture of green sand and a chemical bonding agent, preferably a resin binder and cold set in a pattern box to form the cavities for the cast articles. The mold piece insert is received flush in the mold front face recess with the cavities opening to the front face. A plurality of molds, with inserts, are adjoined in front-to-back relationship with the down runners overlapping the cavities for feeding the molten pour thereto.