Create an attractive display by covering a piece of sturdy cardboard with wrapping paper, then plastic food wrap. Stretch and secure with tape. Or cover cardboard with foil or cooking parchment paper.
Cut cake to form guitar body. Cut 9x2-inch strip for guitar neck. Arrange guitar and neck piece on tray and decorate.
This cake can be frosted using 1 container of frosting. If you like a generous amount of frosting, you may want to have another container on hand.
Freezing the unfrosted cake pieces keeps crumbs in check so they won't get into the frosting.