union(){
difference(){
   color("black") cube (size=[70,70,20], center=true);
color("gold") translate([0,0,-0.7])cylinder(h=20,r=33.5,$fn=100);
}
color("gold") translate ([30,30,-14])sphere(r=6,$fn=100);
color("gold") translate ([-30,-30,-14])sphere(r=6,$fn=100);
color("gold") translate ([-30,30,-14])sphere(r=6,$fn=100);
color("gold") translate ([30,-30,-14])sphere(r=6,$fn=100);
}