I have been able to get a couple guitar shipment boxes from my local music store. They receive them and often have no use for them. You will probably have to cut it down a tad. I have also cannibalized other large corrugated boxes.
You might make your own box if the local music store can not give you one. I would be hard pressed to ship something so beautiful though. Lots of bubble wrap and peanuts...
Rigid foam insulation is light weight and can also be a good friend to keep things from shifting around in the box.
I tape together two identical boxes (maybe amazon boxes or Bark boxes), cut a channel between them for the neck, and bubble wrap the instrument. Peghead and body are both protected / cradled that way. Sorry ... a picture would be more helpful.