Graphs have never been so cuddly!
We used the Adafruit Capacitive Touch hat for Raspberry Pi. Grab the git repo for the chip here:
git clone https://github.com/adafruit/Adafruit_Python_MPR121.git
I modified the keyboard.py example to map letters instead of arrow keys.
The diff is included in the file patch.diff. Apply with:
cd Adafruit_Python_MPR121
git apply ../patch.diff
Running the keyboard example maps the touch sensors to key presses which are
handled in index.html, which we ran fullscreen in Chrome.