Ben Purdy is a designer and technology artist who was working on a projection-mapping project when his brother mentioned that a projection sample looked a little like a Minecraft block. Inspiration thus hit Ben.
It appears that the projection device is within this box [Correction: It's outside the box], putting an image on all six (or, well, five) sides. Purdy says that a piezo element connected to—what else—a good ol' arduino tells the computer when it has been struck, and then to change the projection.
Minecraft in Real Life [Ben Purdy. h/t Asa A.]