Parallel line development is used to develop patterns of square, rectangular and cylindrical shapes (prisms). The method divides the surface into a series of parallel lines to determine the shape of a pattern.
The top and front views are divided into twelve equal spaces.
The parallel lines give us the chord lengths which are then transferred to the stretch out, which is the circumference. This is also divided into twelve equal spaces.
The diagram below shows parallel line development. On the left is the development method for a truncated cylinder. On the right is the stretch out pattern of the shape which is then transferred onto the metal.