Magnetic strip

Gifts are tagged with a very long thin magnet.  The magnet is embedded with a message decoded by magnetic decoding film.  Very easy to make.

Cheap magnets often found attached to refrigerators across the globe can also be purchased in long strips.  It turns out that you can use a strong “rare earth” Neodymium magnet to write messages on the cheap magnet strips.  You can buy green magnetic viewing film to display the message.

Magnetic Strip Reader
Magnetic Message Reader