For anybody in the UK using an OpenROV, I have come across the most fantastic flight case. It is waterproof, really rugged and bright orange! I paid £80, which I think is half the price of a Peli case. The foam is pre-divided into cubes so it is really easy to take out the bits you don’t need. I have no connection with the company, I just found them online. It came next day delivery.
I’ve also got some waterproof connectors on order so I can separate the tether and close the lid!