This Hannah Montana guitar cake was made for my 7 year old niece who loves Hannah Montana. I looked at several cakes on this website as well as the guitars associated with Hannah Montana and came up with one that was sort of a compilation of several.
This was my first attempt at a guitar so I first drew what I wanted (I am not an artist by any means, you could do this too!) then I enlarged it on my copy/scanner. It took a few pages and I had to tape them together to get the size I wanted. I then taped them to my patio door and put a piece of posterboard over the top so I could draw the outline and make a template.
I made 2 half sheet cakes (Wilton's 11x15 size) but if you made it a little smaller, you could do it with 1. My finished cake size was about 14x35. I use Betty Crocker box cake mixes just for time sake. They are very moist so be careful when frosting them, they move quite a bit and will break off if you are not careful.
The rest is pretty self explanatory, I used junior mints for the knobs, licorice for the strings, made some homemade chocolates for the stars and musical embellishments. I use gel paste for coloring, works nicer than paste. I also sprinkled edible glitter on the cake for some extra sparkle. Decorating the board as well as the cake was important and gave it a little more panache I think.
I also like to use parchment paper instead of foil to cover the cardboard base - just looks more professional I think. My board was two pieces of hardboard taped together. If you use your own cake recipe it might have more weight to it so I would suggest something a little more sturdy. I used Wilton tips 18 and 32 for the stars and the one with the teeth on one side and flat on the other for the guitar neck (can't remember the number). I did not use fondant, I have heard it tastes horrible. I like to have cool looking cakes but being able to eat them is important as well.
I used Betty Crocker frosting. In order to get the cake as smooth as possible I put it in the freezer for a bit and then use a hot cake knife to smooth it out, putting it back into the freezer as needed. A lot of the colors tend to darken over time so it is a good idea to make your cake a day or two ahead of time so the colors can darken properly - especially red and black. If I ever have to use black on a cake I use chocolate frosting and tint it with black gel. At first it doesn't look black, more like a gun metal color. However, once the cake sits overnight you will get the black color you need. Works awesome and tastes great!