Traditional process-I sketched this all out with a pen and ruler. Then I went overtop it with Gray 20% prismacolor markers. I built up the tones with 30%, 40%, 50%, 70%, and 80% prismacolor markers. I Once the marker rendering was done I used a large Sharpe to add line weight. Finally to finish it off I used white acrylic and a white prismacolor pencil to create lights.
Digital- I scanned it into Photoshop and filled a new layer with brown. Then I set that layer to hard light. I then used the dodge and burn tool to do some quick fixes on the shading because what I had on paper was a lot lighter. For the blue lights I created a new layer and just painted them the normal way I do. Here is a simple lighting tutorial [link] to explain my process of creating lights for concept sketches.
Size of paper : 9 x 12
Time to create : 2 hours and 40 minutes.