Oh how I hate cases as I have been through a number of them trying to find the right combination, Cinderella had it easy!
Would highly recommend the nuprol line if cases, nice value and quality and eggshell foam as it's just more versatile though doesn't look as good.
I like to use a couple of 2" velcro strips to secure the foam into the cases. Not had it come away before and allows you to remove as needed (I store cleaning rods behind mine).
For pnp foam I would suggest a can of plasti dip to toughen it up.
The shadow foam is pretty neat, a bit more tricky to get set up but will be nicer than pnp foam. The base fitted nuprol case perfectly but the lid was off and eventually just chucked it and kept eggshell for that bit.
If you want a custom style case & still want the ability to change it now and again then you really need to go with the magpul daka system, either in a pelican vault or magpul daka case.
Let's you play around with it and reconfigure it in a few minutes. Downside is the sheer cost of it, essentially looking at £500 per case, but allows you to store and travel with changing load outs. I did have a look at retrofitting it into a nuprol case but would require silly levels if modification and unlikely to fit well-just need a company to mimic it 🙄
The Shadow foam in nuprol case, completed layout (top foam removed in the end)
Pelican vault with Daka insert (this pic was taken after I got it and not finished at time of picture)