One common production method for lightpipes is the overmold . This method uses an inexpensive light diffused plastic overmolded with a black case to generate a light-pipe.
The “Win” keyboard key is one good example.
“Win” key appearance to the observer.
The black key body has a hole; during manufacturing, this hole is filled with a white diffuse plastic in a process called overmolding.
The backside of “Win” key contains the diffuse plastic part, which serves to mount the key onto the keyboard and to provide light diffusion.
We then flashed the key underside with a phone flash and you can see the glowing windows logo.
The “Win” key is placed over a phone LED flash making the Windows logo glow.