Dan's Data reviews the Superball kit: "It's shiny. It's weighty. It's geometrically... intense. And although it looks like something a Man In Black would use to store spare singularities, you can actually build it yourself."

"Amazing Magnets seem to be a perfectly good source for these things, and their extensive line of steel balls is a neat addition. They don't have any really huge NIB magnets, but that's really just as well; giant NIBs just want to smash themselves, and you. They're about as fun to play with as alligators."

See also his review of kittens. (thanks Tim :)