The tiny form factor of the Pi Zero makes it perfect size to hide in any number of retro objects. I have a lot of old video game accessories in my workshop and was inspired to create an emulation station when I saw a design for a RetroPie NES controller on Thingiverse. RetroPie is an open source script optimized for Raspbian and includes many popular emulators all running through EmulationStation.
You won't need much for this build, the main trick is getting your hands on an elusive Raspberry Pi Zero. I used an original NES controller in working condition with a bad cable.
If you don't have access to a 3d Printer, I have uploaded the model to Shapeways. ~$20.