radius = 8.25;
wall = 6;
top_wall = 6;
len = 40;

module external(radius, wall, len, top_wall) {
    w = len/2+radius+(radius+wall)*sin(60) ;
    h = (radius + wall) / 2;
    difference() {
        translate([-len/2-radius,0,0]) rotate([0,30,0]) cylinder(r = radius + wall, h = len + top_wall); 
        translate ([-w,-w,-h]) cube([w*2, w*2, h*2]);
    }
}

module tube(radius, wall, len) {
    translate([-len/2-radius,0,0]) rotate([0,30,0]) translate([0,0,-wall/2]) cylinder(r = radius, h = len);
}

rotate([0,105,0]) difference() {
    union() {
        hull() {
            //external(radius, wall, len, top_wall);
            rotate([0,0,120]) external(radius, wall, len, top_wall);
            rotate([0,0,-120]) external(radius, wall, len, top_wall);
            translate([radius+wall,0,(len + top_wall)*sin(60)]) rotate([0,-90,0]) cylinder(r = radius + wall, h = wall*2);
        }
        translate([radius+wall,0,(len+top_wall)*sin(60)]) rotate([0,-90,0]) cylinder(r = radius + wall, h = len + wall);
    }
    rotate([0,0,120]) tube(radius, wall, len);
    rotate([0,0,-120]) tube(radius, wall, len);
    translate([radius,0,(len+top_wall)*sin(60)]) rotate([0,-90,0]) cylinder(r = radius, h = len + 2);
}