I have never found one, but my aunt made one and buried it on her property where she lives outside of Savannah Georgia. I tried to find it a few years ago but didn't have any luck. She was living in a mobile home while her house was being built and buried it in the "yard". Once her house was completed, the mobile home was removed and everything grew up in that area now she doesn't know where she buried it.
I made one for my kids(I have twins,1 of each),when they got out of 1st. grade and buried it in a popcorn tin in my compost pile in the backyard.I checked it once about 5 years ago to see if was still shut,it was.I plan on digging it up when they get out of college in 4 years.