Wow, this Guitar Hero Birthday Cake was such FUN to make. My creative juices flowed. I started with two large sheets of cake. I butted them up next to each other. I then took a real guitar hero guitar and traced it with a knife onto the cake and carved it out. I then covered the cake with buttercream frosting. Now the fun begins.
I made my own fondant using a package of jet puff marshmallow, a tablespoon of water and a package of powdered sugar. For taste add one to two table spoons of almond extract. Start by placing the package of marshmallows in a large microwave safe bowl, add the tablespoon of water. Microwave on high 1 min, stir, continue in 30 sec intervals until all marshmallows have melted, add the extract, mix, add powder sugar gradually, this will take time getting it all mixed in. Keep adding powder sugar until dough forms. You may not be able to get all sugar blended in but do your best. If dough is sticky add more powdered sugar.
Now you are ready for color. Separate dough into sections. White will be the largest section, it is for the body of the guitar. I used gel color it, blends better with the fondant. Make sure to wear latex gloves to keep your hands from getting dyed. After all the colors are blended well, roll out the fondant on a corn starch covered counter top. Roll fondant at least three inches larger around than the cake itself (it is easier to trim away excess fondant than to remove and start over).
Now cover your cake. I used a pizza cutter to trim off extra fondant around the cake. Oh, if the cornstarch is visible on your fondant, I spray vodka over the entire cake, it cleans up the fondant from the cornstarch and it evaporates, so as to not leave your fondant sticky. I used an air gun to do this, if you do not have an airgun, just use a soft paint brush. (All details and the Guitar Hero logo are also made of fondant).