difference()
{
minkowski()
{
cube([40,80,16], center = true);
cylinder(r=20,h=1,$fn=180);
}
translate([0,0,16])scale([2,3,1])sphere(20,$fn=120);
translate([10,0,-5])cylinder(8,2,4,center=true,$fn=60);
translate([0,10,-5])cylinder(8,2,4,center=true,$fn=60);
cylinder(18,2,8,center=true,$fn=60);
translate([0,-10,-5])cylinder(8,2,4,center=true,$fn=60);
translate([-10,0,-5])cylinder(8,2,4,center=true,$fn=60);
translate([30,-50,0])cylinder(40,3,3,center=true,$fn=60);
translate([-30,-50,0])cylinder(40,3,3,center=true,$fn=60);
translate([30,50,0])cylinder(40,3,3,center=true,$fn=60);
translate([-30,50,0])cylinder(40,3,3,center=true,$fn=60);
translate([23,-53,0])cylinder(40,3,3,center=true,$fn=60);
translate([-23,-53,0])cylinder(40,3,3,center=true,$fn=60);
translate([23,53,0])cylinder(40,3,3,center=true,$fn=60);
translate([-23,53,0])cylinder(40,3,3,center=true,$fn=60);
translate([33,-43,0])cylinder(40,3,3,center=true,$fn=60);
translate([-33,-43,0])cylinder(40,3,3,center=true,$fn=60);
translate([33,43,0])cylinder(40,3,3,center=true,$fn=60);
translate([-33,43,0])cylinder(40,3,3,center=true,$fn=60);
translate([0,-0,-10])rotate([90,0,0])cylinder(240,3,3,center=true);
translate([0,-0,-10])rotate([0,90,0])cylinder(240,3,3,center=true);
}