Magnet sheets (The kind that you can peel of the layer and stick stuff on them)
Mod Podge or some other kind of sealer
Copy/paste different quotes from the Harry Potter books and movies into an Excel spreadsheet. You can also list magical creatures and places, wizards and Muggles, whatever you like.
Make sure all the fonts and sizes are the same.
Print them out, stick them onto the magnet sheets and cut them out.
If you wish, you can also use Mod Podge or some sort of sealant on them.
DrunkKitty's turorial was taken with permission.