Unless someone has put some sort of trademark on their appearance, no, they can't legally hassle you for making a model that looks like them, particularly if it has some differences. Yes, they could hassle you, legally. Madonna "IS" a trademark & her own brand name. and I could list a few more famous celebs that have trademaked their names and themselves. If you were to make a model out of Madonna even a likeness and stamped her name on it, she could slap a lawsuit on you for copyright infringement.