How to create a 3d model based on any drawing

This is my own method how to start modeling a 3d bodywork (or anything 3d) based on a flat 2d drawing.
For this example, I found the blueprints of the McLaren M8A CanAm, one of the most exciting vintage racecar. This is definitely not the most complex shape to translate into a 3d model but it's a good example.

You need a blueprint with at least a front and a side view of the car. If you also have a rear and a top view it's much better. Any additional detail will help you to be as close as possible to a original drawing.

Here is the original drawing. I just scanned it and saved it in a jpg format, after an image scaling.

Then I import this scanned jpg image to my software in a new clear drawing.
I use then different tools such as curves, splines, arc, circles and so to retrace the shape and most of the more important elements of the vehicle.

Once finished, I copy then paste this sketch into a new clear sketch in a new part...and this is the result :

Same for the top view (here I worked only with the top and side view). I put this top view sketch in a different plan in my new 3d model.

And I start building the surfaces based on these 2 views. Sometimes it helps to have a photo of the vehicle and in case of a 100% original design, it's great to have a real-life good-looking scale model.

After a few hours of work, and after "cleaning" all the construction lines, points, plans, surfaces and sketches, this starts to look like a real bodywork :

Then the shape is refined and improved with fillets, embossed surfaces and draft angles when necessary.
And this is the result of this 3d modeling, after 14 hours approximatively for this particular example:

And this is by comparison the real car photo :