When customers buy a digital book in a store they get a smartphone/tablet covers for their smartphone in the design of the corresponding look of the book. The inside packaging of the smartphone/tablet cover has a barcode which enables them to download the book.
What is the core principle of your idea?
The idea is to enable customers getting a stylized smartphone/tablet cover when buying a digital content (e.g. book) at the bookstore. So they get a physical item (here: cool cover) including a digital item (here: digital book).
Can your idea be applied to different formats (in a bookstore, at a trade fair, at a conference)?
sure... that's the general idea behind it - according to the smartphone/tablet the customer uses.
Would it be possible to turn your idea into a reality, or at least create a prototype of it, at short notice, i.e. by the Frankfurt Book Fair in October 2014?
yes.... can easilky be done. Smartphone/tablet covers are very cheap and available at any online manufactorer for a few cents. Some of them are even for free available to print them via 3D print.
What do you estimate the costs for the prototype or the final implementation of your idea to be?
The prototype should cost not more than a few Euros... Smartphone covers are at about 0.50 € available and the printing should cost only 1-2 €.