mollan

Here's my attempt to deepen shadows, and determine a light source. I hope this is useful.

Hey there. I really like your concept. For the rendering concern, I think you need to define the light-source, meaning, from which way is the light coming in. And besides that, don't be afraid to deepen you shadows, as well. When you've done 'shadow hunting' the highlights will really pay off if done right. Also, I would do rendering exercise of both boxy and cylinder shapes including cast shadows, either imagined or from real life. Your background knowledge will supply your understanding for your concept art. Sorry for the tangent. If I have time, I try to demonstrate what I mean with your work.