For my Seacam superdome I have two solutions, which I believe is similar in size.
The expensive solution that I haven't tried is using the case made by Cinebags.
The cheap solution that has worked on numerous trips, was a home depot five gallon bucket and some dense foam. Buy a five gallon bucket with a lid, cut the bucket down to the desired height of the lens leaving room for some foam padding. Make sure there is enough foam to hold the dome securely and to provide sufficient padding. When I travel I duct tape the lid to the top of the bucket with three or four pieces long pieces of tape. The goal is to close the lid securely but to make it fairly easy for TSA to open and reseal the case if they need to look inside. I leave a polite note on the outside of the lid in large letters explaining that it is a fragile glass dome. Not the most elegant solution, but it was a cheap do it yourself project, and it has worked for years for me.