A sinister but harmless gizmo, rigged to look like an explosive device, was found on a Delta jet at Newark Airport, The Post has learned.

The object — made of a ballpoint pen, wires, a battery, a nail and a phony detonation trigger — was found aboard Flight 1927, which landed 11 p.m. Monday.

It was wedged between two seats that were unoccupied during the flight from St. Paul, Minn.