If you've ever been on a cruise, you know how fun it is to decorate your cabin door.

These little duck-shaped mailboxes are perfect for that.

They're 3D printed with a cute duck design and have strong magnets on the back, so they stick right onto your metal cabin door without leaving any marks.

This is a 2-pack, which is handy because you can use one for incoming notes and the other for outgoing messages, or just share one with a friend in the next cabin.

They're small, lightweight, and add a personal touch to your door.

Plus, they're actually useful for leaving messages, invites, or little surprises for your travel buddies.

Just make sure your door surface is clean and dry before sticking them up – the magnets hold really well that way.