OpenSCAD Procar dreifachsteckdose backplate

The backplate of this Procar dreifachsteckdose was missing. So I designed a fitting backplate.

difference(){
    union(){
        rotate([0,0,0]) translate([0,0,0]) cube([91.4,80.8,2.85]);
        rotate([0,0,0]) translate([28.25,0,0]) cube([4,5,5+2.85]);
        rotate([0,0,0]) translate([58.8,0,0]) cube([4,5,5+2.85]);
        
        rotate([0,0,0]) translate([28.25,80.8-5,0]) cube([4,5,5+2.85]);
        rotate([0,0,0]) translate([58.8,80.8-5,0]) cube([4,5,5+2.85]);
        
        rotate([0,0,0]) translate([0,19.75,0]) cube([5,4,5+2.85]);
        rotate([0,0,0]) translate([0,55.6,0]) cube([5,4,5+2.85]);
        
        rotate([0,0,0]) translate([91.4-5,19.75,0]) cube([5,4,5+2.85]);
        rotate([0,0,0]) translate([91.4-5,55.6,0]) cube([5,4,5+2.85]);        
    }
    union(){
        rotate([0,0,0]) translate([3.65, 35.9, -1]) cylinder(r=11.5/2,h=5,$fn=60);
        rotate([0,0,0]) translate([3.65+84.4, 35.9, -1]) cylinder(r=11.5/2,h=5,$fn=60);        
    }
}