Boy, I can just hear your wife....
Where the H&!! is my towel?
Ya know, that wouldn't be a bad way to package a bow for an airline trip. PVC tubes work ok for longbows but I've had two of the schedule 40 weight ones broken at the ends caps. The good thing about that box for airline travel is that it wouldn't roll around in the baggage transport carts. You could also nail on a simple rope handle too.
At $12 dollars in materials it's also about $25.00 cheaper than a PVC case. I'm pretty sure I spent $40.00 plus on the ones I built but that might be including primer, glue etc. It's been a while.