Measure the playing space of the stage. This measurement will determine the length of the wood pieces. The height of playing space will determine whether you will be able to build a mast or to create the illusion of two decks.
Build from the base upward. Build the ship walls with 2-by-6 and 2-by-8 boards. Place the narrow edges of the boards on top of each other. Attach the boards with 1-inch nails angled at 45 degrees. Cut the boards to varied lengths before fitting them together flush to give a rougher look to the ship.
Attach 2-by-4 boards as supports to the back of the wall, at the far sides, at a 45-degree angle to the ground. Nail the end of the board that is touching the ground to the stage floor or to another board that attaches to the base of the wall, creating a triangular support.
Build the mast or upper deck in the same way as the floor and wall of the lower deck. Use a large, rounded piece of lumber as the mast. The upper deck will attach to the mast for support. Add a carved railing to the upper deck for added effect. Some of the railing may be uneven or damaged to give the ship an aged look.
Paint the ship. Dark brown paint works best. Go over the paint with a piece of sandpaper to give an aged affect. Add accents of black to give the impression of wood rot for an old pirate ship or wreckage.
Attach a flag to the mast with rope. For more support, drill holes into the mast. Slip one end of the rope into the hole and tie off the ends. Paint crates to play as cargo to add character to the ship set.