These exist, you can usually find them at robotics supply companies. There’s some discussion of them in the smart chair project thread. (The topic title is a clickable link.)
I decided to experiment with the smart multi’s today. I had two extras after my move. I had the crazy idea that I could strap them to the chairs in my home office and use them as presence detectors. It works. But in looking at the data, I think I could do more. Just wanted to put this out to the collective and get some opinions.
My first experiment was trying to detect taps on the arm rest. This seemed to work OK, but will require a new SmartApp.
Second experiment was trying to detect if I am leaning back too much or not maintaining the correct posture.
Any other ideas?