It is stock. the boarders are made from the black nylon matterial that is used to line the sides of semi trailers. It is layed out and stood up on the edge, with a pin drove into the asphalt. When you chnge your layout, you pull the pin, tap some cold-patch into the hole and then drive the pin in a different location. Real simple and the walls are soft and flexible with lots of give so that you don't break our car. much better than PVC and Wood!
Am I going back racing?...Hmmm.. Not anytime soon... But soon enough.