Mictator,
I converted Lock n' Load's Tank On Tank board game to 3D in 3 scales, so something similar to your project quest -
3mm units -
6mm units -
12mm units -
We still play Tank On Tank 3D in 6mm and 12mm here locally, but I
really regret selling my 3mm kit off, as it was the neatest variant of the three, and certainly the most portable -
Since it was so compact, we could play two game boards at once (I'd go 3mm if you're still deciding on a scale) -