How can create a sphere ( or other shape) with cubes?

Hi everyone, I need your help if you can. What I want to do is to design 10 types of cubes with different color shades ( from white to totally black) without having the same dimension and with those cubes to fill (create) a 3D shape for instance a sphere or a cone. I have seen some tutorials on Youtube but guess what, I did nothing

[Rik]

Your question is not clear to me. Have a read here and here. It will greatly improve your chances of getting an answer.