Replying to HDPE rail/box

So i found two strips of 6 foot long, 11 inch wide hdpe in my backyard. I unscrewed them off some sled for a snowmachine but thats beside the point. I'm trying to figure out what kind of rail to build with these. I was thinking either one 12' long 11" box, or maybe cut the strips longways in half to make a longer rail. Which one do you think would be funner? Also do i need some sort of coping? Like a couple of pvc pipes flush with it on the side? Thanks for your ideas/thoughts...