AHi everyone, I need to make a guitar cake and I'm hesitating between genoise or Madeira cake? For the stuffing should I use whipped cream or is that going to slip?

I'm not sure what kind of guitar you are wanting but I use any cake or icing.  I bake a sheet cake and carve it in the shape of the guitar and I use rct for the neck of the guitar, kids love that.  I use bc and normally put fondant over that.