Historically, burr puzzles were made from wooden pieces but are now usually made from plastic. Some are made from brass and are very expensive collector's items.
The form of the assembled burr puzzle can be anything from a ball to the shape a human figure, a ship, a bird or a free-form starlike contraption. The wooden burr puzzles are usually precision-made for tight fit and require special wood so that the pieces do not change shape too much in changing temperature and humidity.
