If you google the term "mail art" you can find some really elaborate, even unusual, art that people have sent thru the mail. Apparently you can mail pretty much anything, from a message in a bottle (mailed in an actual bottle) to a rubber koi. (I found those examples on the internet.) These cat postcards were my first attempt at sending something decorated thru the mail; they were stamped and painted- the mouse and heart are cut paper. The heart includes glitter, and the yarn is real. They were sent out for a swap-bot swap, and made it to their recipients in New Zealand, Australia, and Canada just fine. I think I'll work my way up to the message in the bottle, though!