Caleb Kraft used overlapping graham crackers and icing/glue to piece together a functional, edible Google Cardboard viewer whose only inedible components were the lenses (which Kraft says he could have made from edible material.
His build/eat log is a nice exemplar of a maker ethos: getting a weird idea, looking around online for basic techniques and similar projects, iterating through multiple designs, then getting something usable and documenting it (and then eating it, of course).