Go to Fedex or UPS and get the closest match and wrap it like crazy with bubble wrap and dense foam. Tape it so it is tight and secure when placed in the box. There should be no wiggle room when done correctly. If shipping~~take pictures of your process and buy the insurance just in case.
Where Can I Have a Box Made for Speaker?
I have a pair of speakers and only one box for one of the speakers. The other box had to be thrown out after a basement flood. So now I'm short one box. Do you know of a company that would make me a new box? I could provide the original box and packing as a template for a new one. By the way, the company (Mirage) is no longer in business, so I could not turn to them for a replacement.