A soaking wet cotton pillow case works great. I would leave it in the tub or shower while your snake soaks in it, so you don't have a big puddle to clean up. A hair clip works great to clip it closed, but I'm sure other things would work fine. An hour or two in the pillow case should be enough. If there is any skin pieces left on at all, they should be really loose and easy to gently work off with a wet wash cloth. Most of the time you shouldn't have to do that, though.