I have a theoretical question I am curious about and need to know. I have no desire right now to attempt this but may be interesting in the future, like I said a theorectical question.

Here it is: For scratch-building an airplane is it possible to photocopy a set of plans at a reduced setting and build the airplane at the reduced size? Or would it take a professional designer to determine the precise sizes of the motor, fuel-tank, wheels, etc.

Has anyone ever done this? Just curious to know, thanx.