If you do the PVC, just be sure it's of a size that you can always reach the snake from at least one end. I put a paper-towel tube in for my gopher once, thinking it would make a very comfy hide...and it did. He loved it. But when I had to get him out one day, I found him totally wedged into the center of the tube with no way for me to reach him. I had to tear the paper tube away...which of course you could not do with PVC.
The piece Marla has pictured looks very safe. (Of course...it's Marla's! :D )