Building a cube from three different 2D images.

Hi All,

I want to build a 3D cube with some specified dimensions x,y,z, with some initial color like blue. Then,I want to get its voxels and set the color for each one (initially, they were blue, but after some calculations I want to change every voxel's color), I want to distinguish the voxels that represent any of the six faces of the cube from those which represents the internal region.

Can anyone please tell me how to do that?

Thanks.