I have used it and the foam is kinda cubed, so you pluck out the needed depth as well as sideways dimensions, you can also step it downwards so as to support items of varying odd dimensions. It’s pretty decent stuff, I have always known it as pluck foam. I have my SeaDoo Seascooters in the big wheeled pelican cases with the stuff and they have been ok for over 10 years now.
I bought a small one to store my crystalsky with mount attached - they are ok, You might want to get a cheap hot glue gun as well so you can fix any errors!
I tried to take out complete sections and half with a bread knife but turned into a disaster.
What I did eventually do was pull out full depth sections and bought a foam yoga mat and cut that into layers for required depths. Turned out really well actually and you can choose colour but bit time consuming.
I’ve been studying it a bit more too. The lid is quite spongy so what I might do with some shallow items is just pull out one layer deep, so they’re then sitting slightly proud, the foam in the lid should then hold them in place.