The underlying theory of constructing sheet unfoldings is always the same. From the spatial form , the trick is to always look for the true lengths of the important projection lines. The true lengths constructed from the projection lines are interconnected by contour lines and in this way the flat pattern is constructed. This technique is based on the construction method with "ruler and a pair of compasses". In a 2D CAD program, of course, the same technique can be applied as deconstruction with ruler and a pair of compasses, but then digitally.