A few days ago, I dropped an old Hard-Cup Sparkleball I love. Five cups shattered, and there’s no way to repair it. That’s the thing about hard cups. They’re really sparkly, but they crack. Two other important points: you can’t staple them and they are a slightly different size than solo-style cups. BUT they come in more colors!
Here are the instructions for making a Hard Cup Sparkleball. I used to use a soldering iron to melt the cups together, but now I use hot glue. (Master Sparkleballer Carl Boro uses silicon caulk.) From the instructions you’ll learn that there’s a different formula in how you put the Hard Cup Sparkleball together. This is very important. If you try to make it like an Original Sparkleball, it won’t work. You’ll need more cups too.
photos below by Carl Boro, who loves making hard-cup sparkleballs.