Yeah, that was 1979. I bought that when it first came out because Martin Gardner did a whole article on it in Scientific American. If I recall correctly he al

Yeah, that was 1979. I bought that when it first came out because Martin Gardner did a whole article on it in Scientific American. If I recall correctly he also posed the question of which letter combinations would not work in a three-way sculpture like that? But I can think of at least one older precedent, a woodcarving puzzle: can you carve an object that perfectly fits a round opening, a square opening, and a triangle opening? And the answer is just the 3-way orthogonal intersection of those shapes. That is from the 1920s or 1930s.