I'm told that the wooden walkways in Wicken Fen have been replaced with ones made of recycled plastic (wood sitting in a fen nature reserve doesn't last terribly well; I think the plastic will take a lot longer to rot). It's black, it's plastic and comes in similar sizes to planking and studding, but I don't know much else about it, and I'd like to get hold of some to experiment with.
Does anyone have any idea what it might be/where to get it?