AFP cast iron corner hopper. This product is handmade to complement cast, extruded and formed aluminium rainwater systems. Most of AFP’s Cast Iron hopper heads suit round, square and rectangular downpipes. The Aluminium fabrication products range extends from a smaller simpler design to a large flamboyant ornamental cast Iron corner hopper head. We supply all of our cast iron hopper heads in either a primed or painted finish. The standard cast iron corner hopper comes with either a 63mm, 75mm or 100mm outlet.