A 12 x 20mm switch fits perfectly inside the aluminium frame in the front. This is a cover to make it fit nicely.
The cables can run along the whole frame all the way to the back.
Ideal for diverting mains wires or any other wires (Octoprint?) from the back to the front.
Make sure your switch and wires are rated for the switched voltage/current.

Made for Ender 3 v2, probably fits any printer with the same size frame extrusions.

Inner hole dimensions: 12x20mm