Give your Raspberry Pi robot the power of gesture recognition with the Pimoroni Skywriter HAT 3D gesture sensor. The electrical field sensor works with Raspberry Pi A+ or B+ boards to detect the movement of fingers hovering above.
With full Python API you can read off the positional data (x, y, z) and identify common gestures like swipes, taps, and double taps. The sensor can detect movement up to 5 cm away, so it can be hidden behind a non-conductive material, such as acrylic.
The sensor comes fully assembled and can be purchased from Adafruit for $24.90.