A method of forming a cooling passage (240, 340) on a turbine component having a component wall (210, 310) with an internal surface and an external surface, the method comprising: forming an opening passing through the component wall (210, 310) and fluidly connecting the internal surface and the external surface, wherein forming the opening includes a metering section extending from the internal surface to a metering end and a diffuser area extending from the metering end toward the external surface; adding a metal cap element material to close the diffuser area of the opening at the exterior surface and define a diffusion section (242, 342) extending from the metering end to the external surface, the metal cap element material including a projection (244, 344) extending internally of the external surface of the component wall (210, 310) and into the diffuser area to define an internally facing section of the diffusion section (242, 342); and removing a section of the metal cap element material to form the cooling passage (240, 340), the cooling passage (240, 340) extending through the metal cap element material and the component wall (210, 310) to fluidly connect the internal surface and the external surface, wherein the metal cap element material includes a metal backing element (252, 352) having the projection (244, 344) coupled thereto, and further comprising applying a ceramic coating (280, 380) over the metal backing element (252, 352), prior to coupling it across the opening, characterized in that removing the section of the cap element material includes allowing a hole to form through the ceramic coating (280, 380) and the metal backing element (252, 352) to the diffusion section (242, 342) during operation of the turbine component. forming an opening passing through the component wall (210, 310) and fluidly connecting the internal surface and the external surface, wherein forming the opening includes a metering section extending from the internal surface to a metering end and a diffuser area extending from the metering end toward the external surface; adding a metal cap element material to close the diffuser area of the opening at the exterior surface and define a diffusion section (242, 342) extending from the metering end to the external surface, the metal cap element material including a projection (244, 344) extending internally of the external surface of the component wall (210, 310) and into the diffuser area to define an internally facing section of the diffusion section (242, 342); and removing a section of the metal cap element material to form the cooling passage (240, 340), the cooling passage (240, 340) extending through the metal cap element material and the component wall (210, 310) to fluidly connect the internal surface and the external surface, wherein the metal cap element material includes a metal backing element (252, 352) having the projection (244, 344) coupled thereto, and further comprising applying a ceramic coating (280, 380) over the metal backing element (252, 352), prior to coupling it across the opening, characterized in that removing the section of the cap element material includes allowing a hole to form through the ceramic coating (280, 380) and the metal backing element (252, 352) to the diffusion section (242, 342) during operation of the turbine component.