
hull(){
 cylinder(h=5,r=5,center=true);
translate([20,0,0])cylinder(h=5,r=5,center=true);
translate([20,20,0])cylinder(h=5,r=5,center=true);
translate([0,20,0])cylinder(h=5,r=5,center=true);
}
translate([10,10,0])sphere(r=10);