Have in mind that for each part below, we need it two times in order to make two radio chat modules and test the connection. We need the 3D printed case to place everything inside it so download the STL files and print it. Then go to the past tutorial and get the GERBERs for the keyboard PCB and make it. We need an Arduino NANO, an OLED display, the battery with a small USB charger and the radio module. I'm using the CC1101 radio module. Extra, we need a buzzer and a sliding switch.