Raised roadbeds in the yard

[nachoman]

Hey guys, ...roadbeds...
Usually, yards are flat and you can't make out any difference in height whereas the mainlines are elevated.... usually. Rather than laying cork for each line in the yard, I'm thinking it would seem easier to just lay down one big sheet. Does anybody make sheets of cork for this purpose?
On the flip side, it might be easier to go ahead and lay down the cork for each line and then fill in the in-betweens with wall joint compound.
Thoughts?

I have seen it in office supply sotres. It actually comes in a roll shrink-wrapped with plastic.