The Stomachion is perhaps the world's oldest puzzle and it is very difficult to solve. It is attributed to Archimedes of Greece (287 BC - 212 BC). The 14 acrylic precision cut pieces ,1/4" thick, will make a square and also many other interesting shapes, with each shape requiring all the pieces. It comes with 19 other shapes that can be made beyond the square. The square measures 6" x 6" when completed in the frame. The puzzle in the wood frame and cover measures about 7" x 7"
Stomachion is also known as loculus Archimedius and Syntomachion and Ostomachion.
It has been shown that each of the pieces has an area that is a rational fraction (a multiple of 1/48th) of the total area of the dissected parallelogram.
It is believed that Archimedes anticipated aspects of combinatorics. Combinatorics involves finding the number of ways a given problem can be solved, subject to well-defined constraints.
Mathematician Bill Cutler determined in 2003 that there are 536 unique ways to assemble the square shape. See how many you can find. Finding even one beyond the one packaged with the set is a good accomplishment.
There is an amazing story about Archimedes' scrolls, the Palimpsest, which was cut up, written over and eventually recovered through a journey of more than two thousand years. The Stomachion puzzle was found on these scrolls.
There are many excellent websites containing fascinating historical and mathematical aspects of the Stomachion. Just do a web search on the name.