Have you ever seen those pool toys called "noodles"? The foam I've seen used for shadow foam is just like that; Firm closed cell foam, and easily cut with a razor knife. Your tools fit into it like a hand in a glove! As for ease of use- it's awesome! No tools rattling around or sliding, or mixing up. It's always where you left it. Everything is organized and easily grabable. You may have to get creative when shadowing tiny or very thin tools, so that you don't have to "dig" 'em out of the foam.
One of the coolest parts about the foam is that when you look through your tool box- you can immediately see which tools are missing. You can label every tool right next to it on the foam (with a sharpie, if you use light enough colored foam- red foam works good) so grabbing the right size will only take a glance. And when other people use your tools, they'll know exactly where to put 'em back