Henry Ernest Dudeney (10 April 1857–23 April 1930) was an English author and mathematician who specialized in logic puzzles and mathematical games. One of his most famous innovations was his 1903 success at solving the Haberdasher's Puzzle (Cut an equilateral triangle into four pieces that can be rearranged to make a square. Equilateral Triangle to a Square using the same pieces. You have 2 trays with the same size pieces in both trays. 4 primary colours, Red, Green, Blue and Yellow Tray is made from 2 layers of white acrylic Size: 244 mm x 145 mm x 6 mm