$fn = 128;

difference() {
    cube([23,23,20]);
    * translate([3,3,3]) {
        cube(17,17,18);
    }
    translate([11.5,11.5,3]) {
        cylinder(18,d=17);
        }
    color("red") {
        rotate([0,90,0]) {
                translate([-11,12,0]) {
            cylinder(23,d=5);
            }
        }
    }
}