Used parts:
- 5V BMS with dimensions: 17,2 x 28 mm https://pl.aliexpress.com/item/4001196670805.html
- 18650 x2 case with dimensions: 78 x 41 x 21 mm https://pl.aliexpress.com/item/1005002482317489.html
- ON/OFF mini switch with mounting dimensions: 13 x 8 mm https://pl.aliexpress.com/item/32976435586.html
- 4 x countersunk screw M3 x 32 mm
- JST 4P cable