One of my favorite items in my collection of mathematical objects is a glass Klein bottle made by Cliff Stoll. So I was excited when—a few years ago—I saw that it was possible to make a glass-looking Klein bottle out of a Method soap bottle.
Eventually, we bought some of this soap and then used it all up. Today I finally had my first opportunity to make one. In addition to the soap container, the craft required some clear tubing and hot glue. It looks pretty good, I think!