difference(){
color("pink")sphere(r=20, $fn=100);
   color("pink") sphere(r=15.7,$fn=100);
   color("pink")  cylinder(h=70,r=10.7, center=true, $fn=100);
    color("pink") rotate ([90,0,0]) cylinder(h=70,r=10.7, center=true, $fn=100);
   color("pink")  rotate ([0,90,0]) cylinder(h=70,r=10.7, center=true, $fn=100);
}
color("white") sphere(r=11.8,$fn=100);