I was inspired to try this cake by the English lady from Birmingham who submitted the homemade Ben 10 birthday cake 01. I made the cake from a chocolate mud cake recipe & covered it in a thick chocolate butter cream. The icing I used is Regalice (a fondant or sugarpaste) which is by far the best icing I have worked with, very pliable & easy to apply (I purchased it on the internet).
I used some coloured Regalice & some white Regalice coloured with gel colours for the lime green, & brown. For the small amount of skin colour, I just used the liquid food colouring you purchase from the supermarket, just adding it together to get a brown, then adding a drop to the white icing & kneading it in very well.
As I am a novice, I decided to make Ben 1 week early to make sure I could get it right. I took 2 identical pictures of Ben & cut templates for each part. It's good to keep one original picture, as a guide so that when all the pieces have been cut out you know where they go. The small pieces look better over the top of the larger ones (examples: the hair, eye brows, etc.) look better added on top of the head, as does the onmitrix parts added on to the black base.
I cut out 4 face shapes from the icing & when they were dry practiced on a couple using non toxic felt tip pens for the nose mouth eyes, & again on the hands. I put each part of Ben together on baking paper gently pushing them together to make sure there were no gaps, before they dried out.
I made & iced the homemade Ben 10 birthday cake the day before, then when the icing had dried a little I placed the Ben 10 parts on the cake. I used an alphabet mold for the lettering, but do not be tempted like me to make these at an earlier date, as the pieces were so delicate, & had gone hard & brittle, most breaking before I could get them on the cake.
I am only posting this here to show how even a novice can get a good result. Many Many thanks to the lady who posted Ben 10 cake 01, you were a real inspiration.