This is the standard case I use for my go-kits.
https://www.thecasefarm.co.uk/shop/cases/camera/dave-235-d/
Originally I picked it because it was the right size for the 45Ah LiFePO4 battery I was building. As it turned out, it fit neatly into half of my motorbike top box meaning I could carry 4 of these sized boxes between my top box and larger size panier.
I had originally built a go-box specifically to fit the motorbike top box so I had the option of using the motorbike, car or simply a shelf at home to use the gear from.
Using modular boxes makes it more versatile as I could (just about) fit one of these in a backpack with a single radio and small battery, or carry up to four on the motorbike, or put as many as I wanted in the car and of course still use them on the shelf at home.
The cases are IP67 waterproof when closed and you have not drilled any holes in them. I do not intend to drill any holes as I would like to be able to use any of this kit maritime mobile and there is a distinct advantage to having your kit in fully waterproof cases! That does mean the lid has to be open to use any of these kits which is a little awkward in most of the scenarios I intend to use them, but that is the trade off I am willing to make for my specific kits.