A touch control human-machine interface for use in controlling operation of a machine, said interface including: an interface housing (340A,340B,340C); a cover plate disposed on an outer-surface of the housing (340A,340B,340C), said cover plate having a plurality of first electrically-conductive portions configured for touch interaction by a user's finger; a circuit assembly disposed within the housing (340A,340B,340C), said circuit assembly including a circuit board having a plurality of second electrically-conductive portions and a light illumination module operably-connected thereto, the plurality of second electrically-conductive portions being modular components that are separate from the circuit board and which are configured for operable-connection with the circuit board; a plurality of spacer elements disposed between and separating the plurality of first electrically-conductive conductive portions from the plurality of second electrically-conductive portions such that the plurality of first electrically-conductive portions, the plurality of second electrically-conductive portions and the plurality of spacer elements are configured to form a plurality of capacitor devices that are operably-connected with the circuit assembly; said plurality of first electrically-conductive portions being configured for deformation by the user's finger so as to cause changes in capacitance across the plurality of capacitor devices, and whereby responsive to said changes in capacitance, the circuit assembly is configured for generating a control signal for controlling operation of the machine, and, for controlling the light illumination module to propagate a light emission from the circuit assembly through the housing (340A,340B,340C) and cover plate so as to be visible externally of the housing (340A,340B,340C); and wherein said touch control human-machine interface being characterised in that the interface housing (340A,340B,340C) includes a first piece and a plurality of second pieces, the first piece comprising a planar array of annular apertures that are positioned between the circuit assembly and the cover plate, the plurality of second pieces comprising modular annular-shaped pieces that are configured for engagement within each of the annular-shaped apertures of the first piece, and wherein the modular second pieces of the interface housing being shaped and dimensioned to provide for secure seating of the plurality of modular second electrically-conductive portions. an interface housing (340A,340B,340C); a cover plate disposed on an outer-surface of the housing (340A,340B,340C), said cover plate having a plurality of first electrically-conductive portions configured for touch interaction by a user's finger; a circuit assembly disposed within the housing (340A,340B,340C), said circuit assembly including a circuit board having a plurality of second electrically-conductive portions and a light illumination module operably-connected thereto, the plurality of second electrically-conductive portions being modular components that are separate from the circuit board and which are configured for operable-connection with the circuit board; a plurality of spacer elements disposed between and separating the plurality of first electrically-conductive conductive portions from the plurality of second electrically-conductive portions such that the plurality of first electrically-conductive portions, the plurality of second electrically-conductive portions and the plurality of spacer elements are configured to form a plurality of capacitor devices that are operably-connected with the circuit assembly; said plurality of first electrically-conductive portions being configured for deformation by the user's finger so as to cause changes in capacitance across the plurality of capacitor devices, and whereby responsive to said changes in capacitance, the circuit assembly is configured for generating a control signal for controlling operation of the machine, and, for controlling the light illumination module to propagate a light emission from the circuit assembly through the housing (340A,340B,340C) and cover plate so as to be visible externally of the housing (340A,340B,340C); and wherein said touch control human-machine interface being characterised in that the interface housing (340A,340B,340C) includes a first piece and a plurality of second pieces, the first piece comprising a planar array of annular apertures that are positioned between the circuit assembly and the cover plate, the plurality of second pieces comprising modular annular-shaped pieces that are configured for engagement within each of the annular-shaped apertures of the first piece, and wherein the modular second pieces of the interface housing being shaped and dimensioned to provide for secure seating of the plurality of modular second electrically-conductive portions.