Cool technology, totally useless.
I remember a friend of mine designed a virtual keyboard using a red tracker (a red cap for the index finger) and a transparent sheet with the keyboard layout on it. It was a part of his Masters project:
Enhanced high speed XTEA decryption implementation, with a case study for realizing a secured virtual‐smart power grids without modifications to the countries power network through a concept product design based on an XTEA decryption core and a communication translation bridge between Mobile Networks/TCP‐IP/Smart Home protocol and Power line communication
