My daughter wanted a "rock star/guitar hero" birthday for her 13th, so this Guitar Rock Star Cake is what we came up with. I took an actual guitar from the game and traced it on cardboard, then cut that out along with other cardboard strips and made a mock mold of the guitar, gluing the strips along the sides of the guitar cut out. I covered the outside of this cardboard mold in black foil. I then made up 2 batches of rice cereal treats and cut them out to fit inside the guitar mold and put a layer of marshmallow fondant on top of that while it was sticky so the fondant would stay ( you can Google good recipes for mm fondant).
I painted it all black, and then colored fondant with other colors to make the buttons. I used some metal cutters for the word "rockin" once it was on the cereal treats. I used large silver dragees for the silver accents, and ground up nerds candies for her name and age on the guitar, glued on with icing, and then later painted with luster dust to give it shine. The flames were fondant painted with silver dust and just stuck on with water. The "drums" were just single layered cakes, filled and frosted, then covered with black fondant, and a colored fondant ring. The microphone was plastic tubing covered with foil and a cardboard tube microphone (tin foil end) all gussied up. The strap on the guitar was a belt that I glued on to the cardboard part of the guitar, and she can now has something off her cake that she can wear! The drum sticks were a mixture of modeling chocolate and leftover fondant just rolled and sort of shaped into a drum stick form.