I used Super Sculpey for the base of this:
I started by forming a basic shape with tin foil (as advised in the guide that comes with it) then layered up the main shape, baking between each stage (again as advised). I used nid weapons, grean stuff, legs off a Storm Trooper arachnid & the rotors off the plastic Deff Copter.
Apologies for the likeness of part of the male anatomy
More pics in my gallery (
http://www.dakkadakka.com/gallery/images-4179-5352_Blight%20Drone.html)