Here is a clever and practical self-locking envelope that sports the well-known symbol of Lillian Oppenheimer's Origami Center of America (OCA). Michael LaFosse designed this envelope in 1998 when Jan Polish requested that he create a simple model that could be used in a folding-challenge game for the 1998 OrigamiUSA Convention. This being the 40th Anniversary of the Origami Center of America, Michael chose to include the OCA origami sailboat in his design. The 1998 OrigamiUSA Convention Game: Each participant was given an envelope that contained the diagrams for this new model. The catch: The diagram sheet had been torn into pieces! Contestants had to first scramble to put the diagram sheet back together. It was essential that the model be new and unknown, preventing the advantage to anyone who would have been familiar with the folding of an existing design!