We propose a prototyping approach to understanding three orthographic views based on constraint satisfaction and discuss practicability of the proposed prototyping system. Our approach reconstructs 3D objects by solving the constraint satisfaction problem that is equivalently transformed from the input 2D data. We perform some experiments comparing our prototyping system with the handcoded system developed separately in which a set of restoration knowledge is implemented. After evaluating efficiency for several drawing examples, we point out two factors that cause inefficiency and propose ideas to cope with them.