I had a few ideas; Imperial Guard is obvious - but what about a Planetary Defence force, maybe a Mechanicum defence automata, or even a defence platform from a lost Forge World being rediscovered during the Great Crusade.
I want to weather this one up - but the idea is that these would be part of a larger force - mass produced and effectively taking the place of tanks.
This is still WIP, but it's working qute well so far, and I'm even thinking of other variants or maybe making two to I can have a kind of squadron. If you have seen Venus Wars, the anime, then the type of armoured street fighting is what I was thinking for this. If you haven' seen Venus Wars, then do yourself a favour an check it out. It's awesome!
Stay tuned for more!