How to Make DIY Extension cord with build in switch

DIY Extension cord with build in switch. Normal extension cord length is less than 3m. In this video adds six miter to any extension cord. If you build one you can make the cord as long as you want.
Material list 

1) Socket Outlet with Switch 

2) PVC Sunk box 

3) 1 mm Three core wire 

4) Plug top