Whirly board and or a slack line style board like Gibbon balance boards.
The whirly board style with 3 balls is better than the single ball or roller type balance boards because tricks and training across multiple axis at once.
I don't have but want a slack line style. I do have a whirly board and use it while working at my standing desk sometimes. Doing tricks on it is great for when you need to think for a minute instead of actively working. It is super easy to transition back and forth between tricks and standing still actively typing.
