Here’s a balloon ball. Sure, you could just inflate a round balloon, but this is cooler. 🙂
In mathematical terms, it’s actually an icosahedron – a polyhedron with 20 triangular sides. It may look complicated, but because of its symmetry and basic units, it’s actually quite easy to put together. I first saw this on Vi Hart’s web site, where she has posted great instructions for this icosahedron, as well as many other mathematical shapes, such as fractals, tangles, and other polyhedra! Check it out!
To make this balloon, I took three 160 balloons and cut each in half. Each section was then used to make one of the six units. (I wanted to make an icosahedron that wasn’t too big.)
If you’d like to read a mathematical paper written about balloon twisting, check out: Computational Balloon Twisting Theory: The Theory of Twisting Polyhedra, co-authored by Hart, Martin Dermaine, and Erik Dermaine (who was one of my college professors!)