I know I am a few years late to this trend, but I did that thing that used to be huge on the internet and took a hammer to a bunch of aluminum foil and it actually worked! I thought it would be terrible, because every guide I found eventually suggested that you bring out your belt grinder and a bottle of aluminum polish, and I am not a metal worker, so I don't have that. Turns out you can get a very satisfying ball of aluminum with just the foil, a hammer, any kind of flat surface to work on and some toilet paper for polishing.
It's shiny and I made it and I can use it as a stress ball by just tossing it from one hand to the other and feeling the satisfying weight. I love it!
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No, but that's mostly because I don't actually have that many rubber bands around. I have seen one made by a friend and apparently they just get more and more round the larger they get, limited only by the shape of individual rubber bands making it impossible to form a perfect sphere-