Abstract: A method and apparatus for forming chamfered outside corners on a concrete product which uses a body made of molded material and having three intersecting perpendicular arms. Each of the arms has a triangular cross-sectional shape so that each arm forms a chamfered surface at two intersecting planar portions of the concrete product. The outside corner itself is formed by the intersection of the arms and is appropriately shaped to define the desired configuration. Planar forming members are assembled to create the desired cast concrete shape. Triangular chamfer forming members are secured to the form where two formed surfaces are to intersect. Where three surfaces would intersect to form an outside corner in the finished product, the molded body is secured to the planar forming members in an appropriate position to form the desired corner shape.