An output structure for material processing apparatus facilitates field replacement of consumable components, while maintaining important alignments. Contoured surfaces within the output structure mate with corresponding contoured surfaces on the consumable components, thereby facilitating alignment of the consumable components with an axis of the output structure. Material processing apparatus employing such surfaces include lasers and plasma arc torches and, with proper alignment, apparatus performance is improved. Typical consumable components include electrodes, swirl rings, nozzles, and shields. The consumable components can be axially translatable with respect to each other, thereby promoting contact starting of a plasma arc torch. An installation tool for consumable components also serves to align the components with an axis of the output structure.