Stewart Coffin is a prolific puzzle designer. One of his designs has become a series of tray puzzles. First he designed a 5 piece tray puzzle numbered #181. He then used the same 5 pieces and designed #181-A. He then designed #181-B. These were called the Castle and Trunk puzzles including two sided trays allowing another puzzle on the other sides. By adding a sixth piece to replace one of the five, Stewart designed the Housing Project, a two sided tray puzzle still using only 5 pieces. The Coffin Set is all 6 puzzles in the set. There are 6 pieces but you select the 5 pieces for each puzzle shown in the directions.