It's been my experience these free thinking exercises have few specific directions except for the only items that can be used and how they are to be fastened. So I'm going to guess that foam as well as any other outside item isn't allowed. There are lots of possibilities though if you think a little bit. Self fastening just means you can't use glue, tape, etc... it's doesn't mean it has to stay together! That's also how vehicles especially race cars dissipate energy in a crash, they pop apart. You can also look at creating suspension within the container to either support the chip or support the container. Just use your imagination.