module stick_shuttle(l, r=4) {
    difference() {
        intersection() {
            rotate([0, 90, 0]) hull() {
                cylinder(r1=0.5, r2=r, h=r*2);
                translate([0, 0, l - r * 2]) cylinder(r1=r, r2=0.5, h=r*2);
            }
            translate([-1, -r-1, -r/2]) cube([l+2, (r+1) * 2, r]);
        }
        translate([r*2, 0, 0]) cylinder(r=r/2.5, h=r*2, center=true, $fn=10);
        translate([l - r*2, 0, 0]) cylinder(r=r/2.5, h=r*2, center=true, $fn=10);
        translate([0, -r/4, -r]) cube([r*2, r/2, r*2]);
        translate([l-r*2, -r/4, -r]) cube([r*2, r/2, r*2]);
    }
}