Front details were then added to further increase the depth of field (Fig.17 - 18).
There was nothing on the left side of the image to strive against the right side, and so a small machine was added to fill the left and to create a nice balance between the two areas (Fig.19).
I used Photoshop to add lighting and smoke effects. I separated them into many folders so I could manage them easily. Try to do this in the beginning as precisely as you can, otherwise it will cost you more time later on when you have so many elements in the scene (Fig.20).
I then used Combustion to add a Z-Depth channel into the scene. This way it is easy to adjust how much you want to blur the background, and you don't have to wait for long periods of time for rendering (Fig.21)!
It was too saturated at this stage so I applied more colours and increased the lighting intensity twice. However, you have to take care of the mid-tones; it's very easy to lose them after increasing the contrast and saturation. For this reason, I separated them into many layers so I could control each of their values only in mid-tones, shadows and highlights. For adding vitality to the scene, I added a third colour, which is blue and dark blue-purple in the middle area. This way we have a buffer colour between yellow and green (Fig.22).
And here is the final version of my image (Fig.23). Thanks for your time. Comments and critiques are very welcome.