One problem I realized, is that it may not be 100% waterproof...didn't think about that before...it fits closed fairly tight, but there isn't a rubber seal or anything...so when I wash my hands, that could be an issue, especially with a picture.
I had thought about putting seeds in it...like for flowers or butterfly weed, and randomly dropping them out when I'm around town.
My husband told me to put a few hairs from my guinea pigs in there...I laughed and said...how about a guinea pig poop, it is the PERFECT size...then he laughed.
I thought about putting an aspirin in there, but again, the waterproof issue might be a problem.
I think some small stones is probably the answer...or I think I saw on Etsy where someone was selling solid wax perfume...I could probably put a mixture of beeswax and an essential oil in it to make my own solid perfume....in case I'm ever in desperate need of the smell of lavender...ha!