I see people talking about using various tool cases for knife storage, the kind of cases that come with the pluckable foam. I need some foam like this, a solid slab not the pluckable kind, for a project I'm working on. I've done some internet searching and haven't found anything yet. Searching on the internet I mostly find industrial suppliers. I've seen the white or beige foam that is used for upholstery, I'd like to find the dark gray kind.