difference() {
  sphere(r=10);
  #cylinder(h=30, r=6, center=true);
}
#if (true) cube([25,6,3], center=true);

#translate([0,-9,0]) difference() {
  color("green") cube([10,4,10], center=true);
  color("red") translate([0,-2,0]) sphere(3);
}