I have been playing around with creating wrecked models for use in scifi wargaming, and I have a soft spot for 40K even though I don't play so much any more.
I started with Garin's excellent dreadnought model and went to work creating a terrain piece from it. The backpack, meant to be printed separately, is Stewart Pope's alternative pack, just included here for convenience.
The "complete" version is really just for show; I think it will be better to print as separate pieces.
The base and terrain are generated using a fractal terrain generator that I wrote and OpenSCAD, as are the barrel and the little cables sticking out of the broken arm. Everything was then pulled into Blender for editing.
Basically I reassembled the majority of Garin's model from the parts in Blender, combining with the other bits and pieces and merging into a single form for printing.
The "complete" version still has a bit of internal structure, and I didn't try to merge the pack into the body, as I didn't intend that to be printed.