I found this great DIY on www.abeautifuelmess.com. It's a bit to late for Halloween but who says you can't love skulls everyday?
-You're going to need candy! Lots of it! Pick all kinds of different colored candy. If you look at a traditional sugar skull, you'll see that is full of bright colors. Of course chocolate bars can act as the dark areas. They have white chocolate reeses now, so those with white chocolate chips can be your whites. I used a lot of Airheads and licorice for color. There are so many options I didn't even use, like jellybeans, candy corn, and sweet tarts.
The first thing I did was make a rough sketch of a skull, which acted as a guide for the initial candy placement. Then it was just a matter of unwrapping and placing the candy. Of course I had to eat a piece every once in a while, for the sake of quality control, you know. I did the chocolaty dark background first, then worked my way in. The white skull background came next, then the colorful details. It took a bit of time to complete, but I think it was worth it! Luckily I had some help from Laura, she was able to lend a helping hand when I was tired of looking at the thing (I may have been sugar crashing, now that I think about it.)