For this project I have used following parts:

1) 3D Printing parts STL files : (https://www.thingiverse.com/thing:4221893)

2) Mini voltmeter (DSN VC288)

3) 4 x M3-10 Screw

4) 6 x TP4056

5) Switch bouton 

6) Rotary Switch

7) 2 x GX-12

8) Some wire 

9) 18650 Battery Holder