In the mail today, I got some neodymium magnets from my brother Sasha as a birthday gift. They are good fun – largely because of how fundamentally counterintuitive magnetism is. Is just seems odd that things are repelled and drawn together by an invisible force that manifests itself at short distances. The danger to nearby magnetic stripe cards and hard drives is trivial when compared to their enjoyment potential.
The only downside of nickel-plated rare earth magnets is their tendency to snap together violently if you aren’t quite careful. Given how brittle they are, this can send tiny shards flying in all directions. This afternoon’s messing about only had one casualty – one of the four smallest magnets among the fifty found its way between the two largest. The larger fragments of the small magnet are now holding papers to my filing cabinet.
On the plus side, I have worked out how to build a reasonably effective magnetic canon using most of the magnets in the set and the barrel from a Bic four-colour pen. It is also trivially easy to make a compass using all fifty magnets in a line, hanging from a piece of floss.
One day, I want to get a full-sized, absurdly powerful supermagnet of the kind at the bottom of this page. At $50 to $275 apiece, they may have the lowest cost-to-danger ratio of anything you can buy online.