An object lesson on working within the limits of a material comes to mind often:
Years ago my wife convinced me that we needed to train our cats to use the toilet. She had purchased a booklet which made the outrageous claim that cats could be trained to do such things. It told us that the process is simple and begins by raising the cat box slightly higher every day by slipping books under it. In time cats learn to jump up to the cat box to use it, it claimed...
Step two begins once the cat box gets to toilet seat level. You slowly move the box over the seat and remove the stack of books. Now, again according to the book, they are accustomed to jumping up onto the toilet. The next step is to cut a small hole in the bottom of the cat box and slightly enlarge the hole every day ultimately teaching them to perch before relieving themselves. Eventually you remove the cat box altogether.
There was a revolt. The cats took to relieving themselves everywhere but where the book told them to. In the tub, behind the toilet, the sink!!... In a desperate attempt to salvage the situation we deployed sheets of cardboard and duct tape to close off the sink, the tub, the area behind the toilet.. Within a few days the entire room was transformed to a surreal landscape of duct tape, cardboard, books and cat droppings. It was a disaster. It never worked. The cats won that one. They just sat there with that "what did you expect?" expression. We dutifully bought them a new cat box.