For the installation of the sign you can integrate your own switch into the design or simply use a standard switch with the dimensions 17x13mm. For the illumination, just somehow stuff a led strip into the box and fix everything with hot glue. Solder the switch somewhere between the plug and the led strip controller.

It is also possible to 3D-print everything btw. but I never tried that. So I dont no if the design works as a 3D-print.

Have fun :) wirte me if you got any questions