Try letting the sketch breath a little. Leave a lot more paper in the sketch. You don’t need to fill everything. If you use a lighter touch with the markers it can be a bit more painterly.
I took a pass at your concept. Things I changed:
- linework, looser, more expressive, more dynamic perspective
- light metal body, just a few strikes of cool grey 20% and 30% with a little bit of britany blue and cool grey 70%
- lens, cool grey 70%, sharpie, and white pencil
- back housing, orange, use marker lightly to get gradation
Give some of those things a try in your next one.
