1. Put a balloon over the mouth of a small plastic bottle. The bottle is the cylinder and the balloon is the piston! Make hole in side of the bottle that is the size of a straw.
2. Glue the bottle to a piece of wood with the hole facing to the side.
3. Make a frame of sticks to hold the crankshaft.
4.Cut out a circle of plastic about as big as the top of the bottle and glue it to a craft stick.
5. Now you glue the other side of the circle to the balloon which is the piston.