Axles

Pens spin and stand in the air. There are some magnets inside both the axles and the basement, which push the axle by interacting among each other toward the glass barrier, which is put perpendicularly to the axle's axis.

The magnets in the tree are made up in a ring-shape, but one pole is on the external circumference, the other one is in the inside. If we turn the axle changes relative position to the poles and the axle sticks to the basement.