Let us show the schematics. We use microcontroller PCB Arduino Nano R3.0 with Atmega328PU chip on board, but You can use any kind of Arduino IDE- compatible board. We decide to use Arduino IDE and Arduino boot on chip to make programming easy.
We use HC-SR04 Ultrasonic sensor to detect the motion near the Map to switch the Map in the work mode and vice versa. When HC-SR04 feels some in 20-30 cm the controller make the invitation “You can press or pull up any continent out of the map”. We use some delay (30-120 seconds) to avoid frequent repetition of the invitation. The delay timer is reset every time someone touches the touch pads.
We install metal screws M2 (it can be any convenient metal construction as rivet) in continents, and small D8x3 mm magnets. Continents with inserted metal screws are attracted to the magnets. We glued wires to magnets and connect wires to the sensor pad chip Proximity Capacities Touch Sensor Controller MPR121. Four MPR121 can be connected to the one controller by I2C bus. We use only two. Chip in MPR121 board measure the charge flow, and when the charge flow via pin is big enough the chip reports to the Arduino via I2C bus that someone touch or untouch the pad. If the pud is touched the Arduino sends command to MP3 Player via Tx bus, and the MP3 Player plays the file. Button S2 switch the mode of the Map- geography, topology, culture, economy, folklore of the continent or island. Stereo signal from MP3 Player go to the stereo amplifier PAM8610 with volume control. Two speakers are connected. We use 5V powerbank or 6 AA accumulator (6x1.2=7.2 V) and DCDC converter to 12 V XL6006.