How to convert the outline of a complex part into a vector?

Question

Vector editor

I cut on a CNC machine. Let's say a box for a smartphone - you can measure it with a smart ruler and draw a rectangle in CorelDraw with the given length and width. This is understandable.
But what if the part has a complex shape? Just don't measure with a line. How to convert the outline of a part to a vector?
My option:
Put a ruler next to it, take a picture, scale it along the ruler in a vector editor, trace the outline. But it seems to me that accuracy suffers so much.
And how would you translate the outline of a complex part into a vector?
Detail example:

Answer 1

For an example from a subject I see only a variant with manual drawing of a contour. Tracing will give a dirty result for such a picture.
In general, there are a lot of sites for three-dimensional people on the Internet with ready-made models or accurate drawings. I think you can just find a high quality blueprint.

Answer 2

2D or 3D?
If 2D - scan and in the same Corel translate into a vector automatically. You can not think about the scale - the scanner produces the "correct" file.