[paulhauggis]

It needs a magnetic surface to work. How is this practical?

[DanBC]

Skateboard parks; amusement parks.

[bitzerlander]

Maybe a prototype for magnetic roads and hover cars?

[DanBC]

You have to refill it every ten minutes with liquid helium. That skatepark has hundreds of thousands of dollars of magnets in it.

A fun, expensive, bizarrely impractical, toy.