3Dpad is an innovative and experimental system that you can use for creativity, experiments and education.
It consists of a sandwich made up of:

a PCB called an electrode plane
an Arduino Shield
an Arduino Uno

Detection principle:

To detect the proximity of the human hand or finger, we are using the projected capacitive technique. This is the principle of virtually all modern touch screens - except that now we are in the air, relatively far away from the detector surface (10 cm max).

The embedded software
The sketch running on the Arduino UNO will exploit the analog result in order to:

Calculate 3D coordinates
Recognize basic gestures (swipes, push and rotations)
Send it all to a host device on the USB COM port

The evaluation software
Despite the fact that everything is calculated on the Arduino board, it can be usefull for you to have a software for a quick evaluation of 3D-Pad. Made with Processing, runs under Windows, Linux