If you are mailing an expensive cue it is not a bad idea to first wrap and place in a round tube then put that into a triangle so you have an extra layer of protection.
An additional strategy for shipping expensive cues is to send usps express which used to be next day guaranteed but now some zip codes are 2 day but, regardless, I find a dual benefit in shipping this way.
1. This keeps your package in the hands of the post office folks the least amount of time so less risk and better service to your customer.
2. For the approx 20% of the time that they miss the promised delivery time (my guesstimate) you will be entitled to a refund and it's easy to collect on; just go with your receipt to the po counter and they will issue either cash or a money order. The insurance will not be included in any refunds, however.
best,
brian kc