$fa = 1;
$fs = 0.4;

lip_dia = 15.5;
lip_depth = 1.5;
tube_od = 12.6;
tube_id = 6.5;
tube_depth = 18;

difference() {
    union() {
        cylinder(h = lip_depth, d = lip_dia);
        cylinder(h = lip_depth + tube_depth, d = tube_od);
    }
    translate([0, 0, -1]) {
        cylinder(h = lip_depth + tube_depth + 2, d = tube_id);
    }
}