Half of a DIY soldier mold cast
This guy was walking around a park in Minnesota (Como Park ftw!) while searching for metallic objects with a metal detector. In one of his trips, he uncovered a metal cost mold with soldier designs engraved inside of it. That pretty much answers the “what” question, but why did it exist?
Apparently, people in the ancient times of the 1960s and 1970s had DIY soldier mold cast sets. They could insert liquid metal (per one Redditor report) into the cast, wait for it to dry and cool, and have five minutes of fun playing with their new toy soldiers. Why anyone would trust a child to play with molten pewter or lead is beyond us.