First of all, we're not going to lie: This butterfly ball origami project is not a simple one to fold. In fact, you should only attempt it if you're an intermediate or advanced origami student. Second, we have no idea why this star-like object is called a butterfly ball (perhaps because it looks like a cacoon?), but either way it's a very cool modern shape.
We'll use only 12 very simple units, but the assembly is a bit tricky.
1) be patient to put all the units together; once finished, it will be stable
2) according to the diagram, stiffer paper is better
3) you can put a smaller butterfly ball inside another (look 0:09). Paper size is 7.5cm x 7.5cm and 5cm x 5cm