The foam that holds BOMApens in their cherry wood boxes is pretty neat stuff. Nevermind that foam in general is my nomination for the most accurate and useful model of reality. The foam in our box has an oddly sensuous touch owing to its smooth surface skin and the way it rebounds with a slight delay. The slow rebound (also called "slow memory") is because of the foam's viscoelasticity. There is literally something in the foam that's slow moving like honey. This property also makes the foam a superb energy absorber–perhaps, technically, not absolutely required but it makes putting the pen away much more interesting.

The foam is called Poron and it has more going for it than just its sensuous feel. It's also one of the most compression-set resistant foams ever created. Squeeze it for YEARS and when you take the pressure off, it bounces back to very nearly it's original size and shape. No matter how long you leave the pen in its box, it will always be held gently and firmly.

What this means to you is that Poron is a fully archival foam; well suited to holding a pen made to last generations.

Here's a link to the technical data sheets of the manufacturer:
http://www.rogers-corp.com/pmu/Industrial/industrial_tech_info.htm