You can do a an Array of Matrixes (NOTE Matrix must be a structure where you save R, G, B)
it will look something like this:
int MaxX = 30;
int MaxZ = 30;
int MaxY = 30;
public struct ColorM
{
int R;
int G;
int B;
}
ColorM[,,] Area = new ColorM[MaxZ,MaxY,MaxX];
void Main(string[] args)
{
Program p = new Program();
for(int z = 0; z < 30; z+)
{
for(int y = 0; y < 30; y++)
{
for(int y = 0; y < 30; y++)
{
}
}
}
}