Well, I have been spending most of my time working on models of engine parts.
With the large variety of different parts and engine configurations you can use, there is a pretty large volume of art required for the engine designer.
I have nearly completed enough parts to make up one engine, and will post some renders in the next day or two when they are all shiny and production quality.
Next bit of work for me besides art is setting up and tweaking the stats of all the parts for the engine designer, been reading a lot of engine tech articles in preperation for this one!