Unlike “open” input devices, silicone keyboards allow data to be entered safely in greasy, humid or dusty environments. They are very comfortable to use and can be designed in great 3-D shapes through injection molding. There are almost no limits to the shape and color of silicone keypads.
As a rule, the silicone keypads are glued directly onto printed circuit boards, and the switching operation can be performed by means of a click-frog or short-stroke button.
Cretec supplies everything from a single source here: silicone keypad including customized circuit board.