A sliding gate that can be closed off or can allow an electric extension cord to pass through a panel/wall/whatever.

Option 1 allows the gate to slide freely up and down.

Option 2 allows the gate to stop on detents to stay in whatever position you wish.

Ignore the large clips in the video. They are there to hold the gate assemblies together for the videos and are not required in any way for actual installation/use.

I printed this in PLA and it uses #8 screws for installation.