Electronics project: Brohoof ring

[VelvetDivan 96]

I was struck yesterday by an idea for a fun electronics project.  Take a ring similar to this, http://www.etsy.com/listing/126725377/dr-whooves-ring-time-turner-mlp-fim

 

Bore a tiny hole in the face of the ring, install a photoelectric sensor and hook that to a programmable sound chip and speaker.  (You can cannibalize them from 'talking' picture frames and such if you don't want to order expensive parts from catalogs.)  When you brohoof someone while wearing the ring, the darkness of their knuckles against the ring triggers the sensor and thus the chip, playing a 'clop' sound.

 

I'm not positive I can fit all of that into a ring, even a chunky one, so my next thought was to go with a bracelet, but then the triggering mechanism has to change, unless you actually connect it to a ring with a wire, disguised or not.  I suppose you could manage something clever with a RFID tag to make it wireless, but I foresee that causing more problems than it solves.  

 

What do you think?  Are there any electronics experts out there?  Any ponies with a soldering-iron cutie-mark?