[header] How to make a balloon stress ball [title] Use flour for a soft and malleable ball. [step] Pour all-purpose flour for baking into your balloon for your stress ball. This creates a ball that is soft and squishy and will more or less hold the shape you form it into. 
[substeps] You can also use other common powdered baking ingredients that you have on hand, like cornstarch or baking soda. Or use sand, if you have it available, for a slightly grainier texture.