Another item in the Mixtape armoury is the #cupcake plans which have already created a few boom-box as well as cassette and CD cakes as part of the fund-raising.
A couple of attempts are illustrated here.
I'm thinking that a Kit-Kat bar (maybe only 3 instead of 4 sticks?) would make a good base for a facsimile robust but edible cassette? Anyone know of any recipes?