I use a thing called: Plano Sportsman Trunk

Google Search it and it will come up at a number of sites.
I got mine at Sam's Club for around $30.
It's a hard plastic case with 4 snapping clips to keep it closed.
It's got wheels and a handle.

No airline has broken it or charged me oversize for it yet.
It could happen.... but not yet.

That case, some bubble wrap.... I would be confident with mine.

Good luck with it.