The Soma Cube was invented by Piet Hein in 1936 while he was listening to a lecture on quantum mechanics! It consists of seven different pieces which can be assembled to form a 3 x 3 x 3 cube. There are 240 possible solutions. Our version is filled with small polystyrene beads which makes it very nice to handle but it does mean that the corners are not perfectly square. It is a very tactile puzzle. The pieces could be filled with foam blocks to make them more square. The puzzle can be made in any medium weight yarn (e.g DK, Worsted, Sport) and should be knitted as tightly as possible. The pieces are all different and are made with the minimum of sewing (One corner in most shapes). The pieces are not difficult but there are detailed instructions for each shape so it is a long pattern which needs to be followed carefully. Make a see-through box and turn this into a fascinating gift. The box can be used to assemble the puzzle or just to keep the pieces tidy.