[Description]

1. After printing, please use tweezers to remove all supporting materials.

2. Install one or more steel balls (recommended diameter of steel balls is 8mm, maximum allowable diameter of 8.5mm steel balls).

3. When bored, thinking about problems, or feeling restless, hold it in your hand and play with it. You can observe the movement of the steel ball and listen to the sound of the steel ball rolling back and forth in the track.