$fn=100;
difference(){
  hull(){
    minkowski(){
      cube ([50,80,0.5], center=true);
      cylinder(r=1.5,h=1);
      rotate([0,90,0]) cylinder(r=0.4,h=1); 
    }  
    minkowski(){
      translate([-15,0,25]) cube ([20,50,5], center=true);
      translate([0,0,3]) rotate([0,90,0]) cylinder(r=0.3,h=1); 
      translate([0,0,3]) rotate([0,90,90]) cylinder(r=0.3,h=1); 
    }  
}
  translate([0,-20,12]) rotate([0,55,0]) cube([12.5,5,16]); 
  translate([0, -8,12]) rotate([0,55,0]) cube([12.5,5,16]); 
  translate([0,  4,12]) rotate([0,55,0]) cube([12.5,5,16]); 
  translate([0, 16,12]) rotate([0,55,0]) cube([12.5,5,16]); 

  translate([-20,0,12]) rotate([0,22,0]) cylinder(r=5,h=26); 
  translate([-20,16,12]) rotate([0,22,0]) cylinder(r=5,h=26); 
  translate([-20,-16,12]) rotate([0,22,0]) cylinder(r=5,h=26); 
}