ORIGINAL: YHR
I am thinking of modifying this, changing the flat cardboard target to a 3D target like a cube or a tube. This would present the same target from any angle.
ORIGINAL: swathdiver
If you make it to resemble a day marker it will be less prone to being knocked down due to wind or from jerky movements of the tank. The day marker idea assumes you make them out of paper so hits are easily registered.
How big a target area will any of these be? I just find that, by personal expereince, a credit card size target is already hard to aim at and hit at any distance farther than 5-6 feet away.. and that's with the target being stationary. Anything smaller.. and moving.. just might need a pointblank shot...