A tic tac toe board game made using high-precision metal machining technique.
A block of warp- and wear-resistant tool steel, a material primarily used for knives and the like, was wire-cut with an electric discharge machine to form parts, then fitted within an error margin of 0.005 mm. The board in its inactive state is flat and seamless, but the metal parts move at a finger’s touch to yield circles and X’s. When placed standing between two players, the front side of the board shows protruding pieces, while the back appears to sink in. The game is played in its familiar form with two types of pieces added to a flat board, but here the design is of subtraction, with the board itself cut with the pieces.