Stunning work Guido! Looking forward to see it painted.
I also would go with overall green. Maybe this pic could act as a model:
T-72B . It's look nice with the skull
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For russian green color, I personally prefer a mixture with olive green (XF-58) and yellow green colors. And it looks
like this Yes it's pretty light, actually it's a mixture 50:50 with these mentioned colors, but I wanted a faded green tone for this tank. You could also take japanese army green or/and field grey, too. But don't forget too add a bit yellow green/desert yellow (what ever), otherwise it will be a very dark tone.
Btw: T-72BM or T-72B(M) is an unofficial designation. The correct one is T-72B model 1988 and so on.