I am trying to find a large white PVC pipe with a large interior diameter. I am going to slip those over the base of a trellis whose legs have a 2.5" diagonal, as a way to bring the trellis higher. The largest PVC pipe I could find at Home Depot had an internal diameter around 2 inches. Short of going for a sewer pipe, what kind of pipe should I be looking for that would have this approximate interior diameter?