I made this M&M cake for a co-worker who loves M&Ms. I used a the ball shaped pan and made cupcakes. I iced the ball cake with buttercream and chilled it. While it was still cold, I covered it with green fondant.
The arms and legs also were made ahead of time out of fondant. When I need to make something to keep its shape or stand up, I knead gumtex into the fondant, form what I need, and let it sit for a few days. This ensures it will be hard and keep its shape.
Then, I just iced the cupcakes with buttercrem which I made in various colors. I piped on the Ms with a #3 tip. The large M&M I used edible markers for her face, but that could be piped on as well.