A Grill for Secret Writing 2
A grill is a square of paper in which some pattern of square holes has been cut. Take a square of paper with four smaller squares cut out. Place it on another piece of paper and write the first four letters of some text in the holes. Then turn the grill a quarter turn and write the next four letters. Continue for two more turns.
 H. Lysing (J. L. Nanovic), Secret Writing: An Introduction to Cryptograms, Ciphers, and Codes, New York: Dover Publications, 1974, pp. 36–37.