At GamesDay 2006 I purchased a box of Ork Kommandos. I recently got the Kommando with a Burna to add to the force.
Having put the model together, I added some slate and modelling sand to the base.
After much thought I decided I would stick the fuel tank on the back of the Ork as painting it separately seemed a lot of extra effort.
The next stage was to give the model a black undercoat.
See the full workbench feature on the Ork Kommando with a Burna.