If you still have a little head motor skills, with a free app you can control everything you control with your fingers by moving your head. The setup is simple and supported by an assistant that guides you through the necessary steps. The App EVA Facial Mouse can be downloaded via the Google Playstore. Here you can also find the official video. But also on the net you can find many videos in different languages.
Important condition for a good function is a stable position of the device. There is a large selection of brackets at the usual online dealer, for various devices and assembly, for little money.
Of course Smart Letter Board is also so easy to use, due to the few large keypads a selection is much easier than with the usual on-screen keyboard. You can also communicate quickly with the possibility of storing your own phrases.