BlueTooth Speaker - 2" Speaker

- 3 batteries (this is the maker's mind)
- Bluetooth amplifier XH-A158 (Manual volume adjustment is convenient to use)
- 2 inch speaker
- Charging module 134N3P (It seems to be convenient because it is used for both charging and discharging.)
https://www.thingiverse.com/thing:1746166 -> power_bank_o_1.stl
- I can't see it in the picture, but I used the XL6009 step-up module to send a stable 5V to the amplifier.
- Circular switch KCD1-105 (It is 16 pi.)
- Assembling round head screws (wrench heads are also required)
8 pieces of M4 * 8 ~ 10 / 8 pieces of M4 * 16 ~ 20 are required.