I wanted to re-create the gun as accurately as I could, so I started looking for information on the gun. I found a few useful images and pdf's on the Walther website. I also bought a authentic replica of the gun (BBgun) which was very helpful to understand the shape of the gun.
Using a drawing of the section of the gun, I started with the easiest part, the top of the gun which is mostly made of flat faces
Starting with the front-end, the middle, and then the back.
With the way that part of the gun is, I did not have to use too many faces.
The rear of the gun, which we don't see in the final image and I started adding some details.