The Arduino, of course to run the code and 9 dot matrices modules. I've tried more than 9 but the library can't do more than that so 9 is max. To receive wireless data I've used the HC06 Bluetooth module and to get the real time, I've used a DS3231 real time clock. We need a few more parts to regulate the voltage and charge the batteries. And yes, we need 2 18650 batteries with a 2S BMS module to charge them. The case is made out of plywood and with carbon fiber vinyl on top.