difference() {
    union() {
        cube(size=[19,17,32]);
        translate([-0.5,0,24]) cube(size=[20,17,8]);
    }
    translate([19/2,16+105,-1]) cylinder(r=105, h=100, $fn=256);
    translate([-20,3+5.5,3+6]) rotate([0,90,0]) cylinder(r=3.25, h=100, $fn=256);
    translate([-0.5,17-3,6]) cube(size=[20,3,6]);
};