

Need help rotating boxes
So I started this week with the box rotating grid
and Im facing a one problem only with it
that is with rotating the box downward
I know that the right and left sides of the box r converging toward a vanishing point below , but I kinda find it HARD to find the right proportions to the top-front face of the box ( in these red circles ) when it's rotating down
So is there any trick to find that right without EXPANDING the box itself?