Once a year, like an alarm clock that goes berserk on schedule, a thing called Maker Faire sets up in Queens. The Faire is science, dressed up as carnival and art and cartwheeling. There is, for instance, a life-size mousetrap arranged in a giant circle. A bowling ball drops, as it must, from a platform. It lands on a trigger, which flips another level, and 700 feet and a dizzying array of simple machines later, a bank safe drops onto a taxicab.

There is a lock-picking workshop. Do-it-yourself electronics with open-source circuit boards. Workshops on 3-D printing. Drones. A Bellagio-style fountain of Mentos-foaming Coke bottles.

For two days every autumn since 2010, the Faire has been held at the New York Hall of Science, housed in Queens at the site of the 1964 New York World’s Fair in Flushing Meadows-Corona Park. Last year, the Faire had 95,000 visitors, according to the Hall of Science.

But this year, the organizers of the Faire, scheduled for Oct. 1 and 2, have run into the extraordinary obstacle of a professional baseball team in possession of a sweetheart lease underwritten by the public. The New York Mets and the team’s various business arms control a million-square-foot parking lot — built by the public, on publicly owned land, but operated by the Mets, who collect virtually all the money from it.