i used foam from an old slide in camper to build my last boat and it just so happens the other day the wind picked up my buddys slide in camper and tosed it on the gound.

so i will be getting the foam out of it for the seats on my new project.

i have heard of people using couches and baby matresses.

just make sure you put a few holes in the plywood to alow the air to escape. if you dont you will end up with long lasting but imprints.

and what ever water makes its way threw the vynil will get out there also
just a question about the foam for the side panels what about that hypoalergenic foam carpet padding for the pannels it does not alow moisture to penitrate the surface that was my thinkg for my side panels 2 layers of this stuff. super durable and firm