difference()
{
    union()
    {
        rotate_extrude($fn=360)
        polygon(points=[[3.1, 0], [17,0], [17,1], [15.65,2], [15.65,8], [17,9], [17,10], [14,10], [14,3.5], [7,3.5], [7,12.5], [3.1,12.5], [3.1,0]]);
        translate([-7, 3, 3.5]) cube([14,9,9]);
    }
    translate([-4, 4.5, 4.9]) cube([8,2.2,8]);
    rotate([90, 0, 0]) translate([0, 8, -13]) cylinder(r=2.5, h=12, $fa=1, $fs=0.5);
    translate([-4, 13, 3.5]) cube([8, 8, 8]);
    translate([-5, -20, 3.5]) cube([10, 12, 8]);
}
translate([-4, -12.5, 3.5]) cylinder(r=2, h=6.5, $fa=1, $fs=0.5);
translate([4, -12.5, 3.5]) cylinder(r=2, h=6.5, $fa=1, $fs=0.5);
difference()
{
    translate([-9, -4, 6]) rotate([0, 0, 45]) cube([2.5, 5.5, 5], center=true);
    translate([-11, -2, 4.5]) sphere(r=3, $fa=1, $fs=0.5);
}
difference()
{
    translate([9, -4, 6]) rotate([0, 0, -45]) cube([2.5, 5.5, 5], center=true);
    translate([11, -2, 4.5]) sphere(r=3, $fa=1, $fs=0.5);
}