If you found the cake on CC, why don't you just PM the decorator and ask.
i would use gum paste rolled to 1/4 thickness or thin Styrofoam covered in fondant..
Just so ya know, it's called the "neck", not the handle.
On my guitar cakes, I've made the neck out of cake and used a strip of fondant the same color as the cakeboard to create the illusion of a thin neck.
very nice cake, thanks for the help.