Ingeniousity.net

I was at the pool yesterday, and they have introduced a new system in the changing rooms. Instead of just leaving your clothes and wallet on a shelf (Taiwan is a very safe country in that regard) you now have to put a coin in a slot and use a locker.

 

You get a key on an elasticated band that goes around your arm or leg, and this key tucks inside a rubber sheath to stop it chafing against your skin as you swim. It swivels into the sheath, and you position it so that the pivot is at the 'top' and the key hangs down inside the sheath.

 

But as soon as you start moving, especially when swimming, gravity comes into play and the key falls out of the sheath. Either you're swimming, in which case you're horizontal, or else the key just decides to turn itself upside down anyway. The end with the pivot is heavier than the other end so the whole thing flips and then the key swings out. It's not a big deal, but if the key won't stay inside the sheath then who needs the sheath anyway?

 

So, why not a key that slides in and out of a retractable sheath? Maybe with a lock, or maybe just relying on the fact that the 'inside' end of the key would be heavier and therefore pointing downwards. If you're going to have a sheath then it should perform the function of a sheath, otherwise there's no point having it. So design one that works.