I might look into PEX tubing. I've never heard of it. What's it used for generally?
I have that exact foam padding already. I used to use it for a special kind of artwork. I have small pieces I have used in the past for a padded backing when I do scrimshaw artwork. It holds the ivory nicely in place, is non slip and also works well as a quick wrap that protects the small pieces of ivory from scraches since I would take it with me to work and work on the art projects from time to time. I don't intend to irritate anyone about it being ivory. This material was bought years ago, and originally came from a resource that recycled old piano keys, when they were made of ivory back in the day. A company that is carefully scrutinized and monitored by the government, is allowed to sell a volume of old stock ivory from materials left over from a very long time ago. I bought four small pieces like this, and if I do it again in the future, it will likely be mammoth ivory, since they were extinct and dead long before mankind came along a decided to shoot an animal for its teeth.
I don't want to wander off topic too much. But I'll share the two pics here.
I pulled up a few pictures of the padding and artwork, if anyone is interested in fine art as well. I don't want to get completely off topic, since this is a coffee forum, but I'll share them since they have to do with the padding you pointed out. I edited one image so that it wouldn't offend anyone. I don't think it's distasteful, but I will remove the one, which is of a model if it's somehow deemed inappropriate. That was the first one I ever did, back in 2006. It took hours and hours tapping literally several hundreds of thousands of small dots with a sharp tool. Then a nice dark brown oil paint is rubbed onto the surface. The small dots retain the color after I rub off the excess.

The second one is a work in progress that I haven't touched in a while. It might look good when I finish it, if I ever get around to it.

I had considered trying to figure out a way to scrimshaw an image of a coffee bean into the white cap on top of my tamper as well. The Delron material is quite hard, and a completely different surface to work with. I don't know if it would work.
Fresh out of the roaster: Hawaii Ka'U Typica, Ethiiopia Gedeo Worka, El Salvador Kilimangaro WP
Next batch: Nothing yet!