The CT gives dimensions for the stone box.
“The Orators of Mormon,” Mercer Press (Pennsylvania), c. April 1832 in Catholic Telegraph (Cincinnati, Ohio), April 14, 1832, 204–5
In 1827 a young man called Joseph Smith . . . went into the township of Manchester, and there, on the side of a hill, found in a stone box, or a square space enclosed by stone on every side, the plates on which the revelation was inscribed. The box in thickness was about 6 inches, and about 7 by 5 otherwise; the plates themselves were about as thick as window glass, or common tin, pure gold . . .