I have done a huge elmo cake, have posted the picture on my profile too. I had done the red, by adding various Wilton reds and little brown and the best part was, after a few hours the color deepend to become the perfect elmo red color. I had used many shades of wilton red, thankfully the icing hadnt got bitter. the perfect red is all a game of continual addition of red and then hoping it to turn into that perfect red in the next 7 - 8 hours. Best of luck.