I made this Ben 10 Alien Force Cake for my son's 7th birthday. I used 5 cake mixes. I made the bottom of the cake two layers. I used a 13x15 pan and used 2 boxes in each layer. I topped it with a round 9" pan and used 3/4 of one box of cake mix.
I frosted the top with decorator icing (I bought the tub at Walmart for $12 and it frosted the whole cake). Spread a thin layer over entire cake. The top round I decorated as an Omnitrex. I made a buttercream fondant that tasted like real frosting. It wasn't like regular fondant where you peel it off because it tastes so bad. I got the recipe off of allrecipes.com. It was a little greasy but was easy to work with.
I made the fondant recipe first and then separated it and used food coloring to make the grey, green and black. I rolled out a thin layer and covered the entire round cake with the gray fondant. Trim it down to fit. Then I rolled out a smaller green round and cut out the Omnitrex shape. I rolled it out on wax paper and topped it with wax paper and then rolled it backwards onto the top wax paper in order to place on the cake.
Then I made ropes out of the black fondant and made the circle and borders to finish off the Omnitrex. Then I rolled out a black layer for the watch band and placed on each side.
Back to the decorator frosting, frost the remainder of the cake and leave some frosting for the trim. Color the trim green. Use the start tip to place the border on the cake. Use the dot writing tip to write the words on the watch band and side of cake. To finish off the trim, roll out the three colors of fondant and use a start cookie cutter to cut out different colors of stars and place on the cake. Then roll tiny balls out of the colors and place in a row green, grey, black, etc.
I topped it off with Ben 10 creation chamber figurines. You can buy a box of 8 in one set at for about $15-$20 depending on where you get it.