difference(){
    sphere(r=20, $fn=100);
    sphere(r=19, $fn=100);
    translate([0, 0, -60])cylinder(120,5,5);
    rotate([90, 0, 0]) translate([0, 0, -60])cylinder(120,5,5);
    rotate([0, 90, 0]) translate([0, 0, -60])cylinder(120,5,5);
    rotate([45, 0, 0]) translate([0, 0, -60])cylinder(120,5,5);
    rotate([0, 45, 0]) translate([0, 0, -60])cylinder(120,5,5);
    rotate([0, 0, 45]) translate([0, 0, -60])cylinder(120,5,5);
    rotate([0, 0, -45]) translate([0, 0, -60])cylinder(120,5,5);
    rotate([0, -45, 0]) translate([0, 0, -60])cylinder(120,5,5);
    rotate([-45, 0, 0]) translate([0, 0, -60])cylinder(120,5,5);
    rotate([-45, 0, 45]) translate([0, 0, -60])cylinder(120,5,5);
    rotate([45, 0, -45]) translate([0, 0, -60])cylinder(120,5,5);
    rotate([45, 0, 45]) translate([0, 0, -60])cylinder(120,5,5);
    rotate([-45, 0, -45]) translate([0, 0, -60])cylinder(120,5,5);
     rotate([-90, 0, 45]) translate([0, 0, -60])cylinder(120,5,5);
     rotate([90, 0, -45]) translate([0, 0, -60])cylinder(120,5,5);
}
difference(){
sphere(r=14, $fn=100);
sphere(r=12);
}