... voice, message, phrase or any soundActivated way: pull-tab switch, buttons, light sensor, vibration sensor, shadow sensor or rocking ... switch.Main component: speaker, PCB, IC, batteries, switch, wiresSpeaker available: 40mm, 29mm, 27mm,21mm ... sheetStep 2: tear down the yellow paperStep 3: stick on the greeting cardStep 4: close the greeting card and re ...