What about using a heavy-duty cardboard tube?
I've had many cues shipped to Thailand, and the containers that arrive in the best condition are tubes just under 3" in diameter with a cardboard thickness of 1/4" (you could stand on it and it would easily support your weight)- it will hold a butt and two shafts and packing material with no problem.
The triangular boxes that are a great size to hold a cue tend to take a beating and lose structural integrity- the tubes are great, and are probably much cheaper.