It's possibly hard to tell compared to the last photo further up the thread - so here's a side by side comparison. Arms are in progress to the same stage but not added, because it all overlaps quite confusingly and makes detail work tricky for me.
The inner workings received a coat of AK Interactive Rust Streaks, then I pulled off the excess with cotton buds. Haven't used this before, but will be doing so again. You may cry "he's ruined it!" at this point, but actually I'm really happy with how its turning out - the colouring is a little more severe in the photo than real life, and pleasingly uneven. It looks like an unloved machine that hasn't been looked after - and may be a little pissed off by this.
Deciding on how or even whether to apply rust onto the exterior metal plates. I think I should, but any thoughts or comments for more experienced weathering wizards?
Last up, a recently backed Kickstarter project - the Basius series of molds to apply your greenstuff to for custom bases. It'll be a little while until they get a run out, but they look the business and the project was well run - even if the project page was laid out like a Geocities escapee :D
But they stack oh so neatly!