Calling itself an "exercise in interface archaeology" the Tworse Key is a portable device created by Martin Kaltenbrunner that interprets your taps and outputs the final message via the Twitter API. It is connected to the internet via a standard LAN connection and an embedded Ethernet enabled Arduino board.
This project is fully documented under and Open-Source license (code here) in "order to illustrate the Open Design process for beginners, who are aiming to realize a simple but appealing Arduino project". The Hardware requirements include finding an old Morse Key (they suggest Ebay) and the creators spared no details in the originally design by even included a cloth covered Ethernet cable to give it that extra little touch.
Image Source: TworseKey