i’ve been told you can mail just about anything categorized as non-lethal through the postal system with proper postage affixed (examples include: an old shoe, a cocount, and a ziploc bag of toenail clippings).
artist riitta ikonen tests this theory with her mail art project- 100 postcard-sized objects sent to see which ones reach their final destination. (sneak peek: second row down, fourth from left > sardines in glue.)
via riittaikonen.com
