A few points relevant to system structure to consider are, depending on the keyswitch used, the illumination is either already built-in or is installed next to the keyswitch if required, the plunger is either placed on the keyswitch or is already built-in, the typical tactile properties of RAFI short-travel keyswitches can be ensured by maintaining the specified distance from the overlay to the PCB with distance bushings, and embossing over the keyswitches is recommended for an overlay.