Front piece of a EU style socket. Fits perfectly to Busch-Jäger parts but might be suitable for other brands as well.

You will need a lot of support. Make sure that the orientation of the support material is rotated 90 degrees to the orientation of the support knobs on the back. Don't skimp on plastic. Print it with a wall thickness of 1.6mm to the sides, 1.2mm to top and buttom and 40% infill.

Designed with FreeCAD, source file included.