For a firm stress ball, use flour, baking soda,[2] X Research source or cornstarch (a white powder called cornflour in the Commonwealth). For a looser stress ball, use dry rice lentils, small beans, or split peas, or fine play sand from a hardware store. Mix a small amount of dried rice into flour for something in between. This is also more durable than flour alone.
This is easiest to do with a clip or assistant to hold it closed. This can make the filling process messier if the air escapes while you’re filling it.
If it clogs, use a pencil or spoon handle to clear the opening.
To release the air, pinch near the neck and separate your finger and thumb slightly. Too wide an opening can blow flour everywhere. [4] X Research source
