OutletBox
This is an adapter for computer power cord to outlet. Personally, I use it in my classroom when we have desk computer but no outlet. Can be used for doing extension.
To do thids thing, you need :
IEC320 plug :
https://www.amazon.ca/gp/product/B01C8CRIKM/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1
Wire AWG 18 or bigger.
Enjoy ;)
Note :
I am not responsible for any problem related to this concept. Take care to do good wellding. A bad wellding can cause fire or damage.