Found my first Munzee-Letterbox hybrid yesterday. Wizardsnake planted a Munzee with a custom made stamp. It’s listed on the Munzee site. What a surprise. I didn’t have my letterbox gear with me so I ended up going back a little later to stamp up. This stamp was quite unique. It was made out of a soft plastic material. My guess is it is crayola modelling air-dry clay and it was pressed into a mold.