This is one of these designs that keeps coming back at your drawing pad. I already got two takes on it.
First sketch was shaded fingering over a tablet with Sketchbook Express. The second, with more functional mechanics, had been shaded with grey water based markers and a paint rollback highlighter
Then it took very little to made me model some pieces in 3dmax.
Those new sketches are compiled at 2d Works&Sketches page in this same blog.
As always C&C very welcomed