$fn = 200;

cylinder(d=4, h=25);

*difference () {
    union () {
        translate([0,0,2 /2]) cube([10,10,2], center=true);
        translate([0,0,10 / 2 + 2]) cube([10, 2, 10], center= true);
    }
    translate([0,1,7]) rotate(a = [90, 0, 0]) cylinder(d=4.2, h=2);
}