Make magnets, of course!
This tutorial really is so simple it doesn't even need a tutorial...
You need corks, of course... ;-)
You also need a hot glue gun, and some magnets. But -- a word to the wise:
Pay attention to your magnet strength. These were much too weak to hold my cork onto the refrigerator -- which meant an extra trip to the craft store. *Annoying*. ;-) Try to find something a little heavy duty for your keepsake magnet.
These were just the ticket! Heavy and strong. Woop!
You just need a thin layer of hot glue, then firmly hold the magnet to the bottom of the cork for a minute or so. And then...
Proudly display your custom creation. :-)