T puzzle

Despite its apparent simplicity, it is a surprisingly hard puzzle of which the crux is the positioning of the irregular shaped piece.

[5] The T-puzzle became very popular in the beginning of the 20th century as a giveaway item, with hundreds of different companies using it to promote their business or product.

They usually came in an envelope with instructions and an invitation to write to or call at the company or local dealer for its solution.

[13] A particular nice presentation of the puzzle appeared in the October 1913 issue of John Martin's Book, here shown to the left.

[16] The puzzles presented in this book were proposed to be constructed by red cross juniors for use in the military: "to be used for distribution at canteen centers for the men passing through on the troop trains ... for use in camps, convalescent houses and hospitals" (p. 378).

They note that the puzzle "has proven popular with British Tommies" (p. 394) and give detailed instructions on how to fabricate the pieces and an envelope container.

From the 1930 dates an advertising premium for Mohawk Rugs & Carpets which besides the regular T, features the challenge of making an arrowhead with the same pieces.

[22] In the same year a giveaway for Eberhard Faber's Van Dyke pencils featured 14 different shapes to form.

And even when the pentagon piece happened to be placed properly, it was mostly not recognized as part of the solution, as a match with the T is not easily seen.