ESP32, MPU6050, Nidec 24H brushless motors, 500 mAh LiPo battery.
Balancing controllers can be tuned remotely over bluetooth.
Example:
Send p+ (or p+p+p+p+p+p+p+) for increase K1.
Send p- (or p-p-p-p-p-p-p-) for decrease K1.
The same for K2, K3. Send "i", "s".
About schematic:
Battery: 3S1P LiPo (11.1V). Buzzer: any 5V active buzzer. Voltage regulator: any 5V regulator (7805). All red connections not nescesary for this project! But if you are designing a PCB I recommend making these connections. Maybe I use encoders in the future, you will be able to use the new firmware without any changes.
How to build:
If something doesn't work, try the motors test sketch. It tests all motors, rotation directions and speeds. This helps you understand the problem is in software or in hardware.