This gun turret was based on concept by Malaveldt + real world references. It is untextured, but lit in Marmoset.
Concept art by Malaveldt
This is a cut away image of a gun turret, based off of concept art. This was created in Maya and rendered/lit using Marmoset. It's an older piece that I always liked, but never got around to texturing it (maybe one day!)