Not long ago I made a post where I located tons of soft foam.
In the dumpster in the back of a furnature store.
I did some trashing today and found rigid foam.
I don't think its good for absorbing vibration but if you have one of TH tote boxes that come with no legs this stuff will do the job.
And I got a full box of it from a dumpster in the rear of a sporting good store.
Now if I can only find one big enough to lay down beside that steam grate.........
Well at least check out the PIC.
It's 3 layers glued together

Yep, looks like some closed cell polypropylene foam -- you called it right: good for impact resistance -- comes in a vriety of densities, too, depending how much impact you have to resist. Bad for vibration isolation.

We get computer gear shipped with that stuff used as blocking to hold the things in place in their boxes. It does have some use.

Hi Al,
I cut that 1 block into 4 nice chuncks and made feet for my TH tote box.
Your right about the closed cell foam not being good for vibration but I have tons of the soft open cell foam(another dumpster find) located in the back of a furniture store.
I cut a nice RX size hole in it and I have it velcroed to the bottom inside of the plane.
We got hit with a storm last night and have 16"of snow and 30+ MPH winds and it's still coming down hard.Road crew Men are doing a very good job but I have to dig out the wagon so I can hit the stores tomorrow.
Thanks for the post