I designed a cover to complete the E14 socket designed by "omskradio". Use a 5mm M3 screw to fix it to the body. Be cautious about the screw length; if too long, may make contact with the wires inside.

The cover have enough space for a pair of terminal blocks too, which makes it a professional installation ;)

The file for nut was recommended to be resized by 108% in X and Y in the slicer to fit the body screw. For me 108% is too loose and 103% fits best.

Please see the original design for a photo of the wiring.