Patent ID: 6896833

Claim:
A method of manufacturing a device for flush mounting in a wall opening, comprising the steps of: forming a model of the device comprising a body having a perimeter and a peripheral flat flange of predetermined width extending around the perimeter of the body, the model having an upper surface; covering the model with a parting film; applying a coating layer of clay of predetermined thickness over the parting film to cover the upper surface of the model and extend down over the peripheral edge of the flange; pouring a shell of moldable material over the coating layer; allowing the shell to harden; removing the shell from the model and coating layer; removing the clay coating layer from the model; placing the shell over the model so that there is a cavity of thickness equal to that of the coating layer between the model and the shell; forming a pour hole in the shell; pouring a liquid mold material for forming a flexible liner through the pour hole to fill the cavity; allowing the liquid mold material to cure to form a flexible liner; removing the shell from the model and liner; peeling the cured liner from the model; inverting the shell and reinserting the liner into the shell; and pouring a liquid cement material into the liner to form a device which is a duplicate of the model.