I was never especially fond of modern 3D graphics, and I've become less so as time went on. So starting around 2011 I've done a bunch of research into now-forgotten rendering techniques such as voxels (not in the Minecraft sense) and wireframe, before settling on sprite scaling as the most simple, flexible and expressive pseudo-3D, a.k.a. 2.5D, technique. The articles I wrote on all these topics remain however, if you'd like to see them, along with my engines and tools.
As for concept art, some of my favorite games as a kid were Elite, Lords of Midnight and The Sentinel. The likes of Space Harrier and Star Fox also left an impression. And more recently, I described a spaceship in one of my stories as "a great mechanical shark", which later inspired me to create one of my better 3D scenes and models, respectively. Hope this helps!