lol, bubble wrap.
You want a material that will give, but not so much that the pressure just smooths it out - know what I mean?
Like Gel Pads, they are useless. When you lay the Gel Pad down on the floor and you press your fist into it, the gel moves away from the pressure, making it uneffective - so take the same idea with the material you want to use.
Make sure, that even with pressure, the material is still effective enough to protect your fellows back.
Or try to find that white stuff that is in my pad. Go to a fabric store *not walmart, they have insufficiant stock* and see what you can find, or a hardware store.
When you come to Lou Don tomorrow, I'll show you what I have so you can get more of an idea. That white thick padding that is in my white pad that my Hubby bought...I showed you it when you came for the Wintec....