Quick update: After a grueling month of waiting for the cheap ebay sensors to arrive, they are finally here! I've hooked one up and I'm in the process of writing some test code to get everything working on the breadboard. I neglected to get the sensor breakout board with level shifters on the I2C lines, so I've switched over to a Teensy for the prototyping since it's one of the few 3.3V boards I have. This also lets me drive each of the LEDs independently from their own pins, which simplifies things. I'm still planning on porting over to an AVR chip for the final board. However, I think I'll stick with 1 LED per pin, so I won't be using an attiny85 like I had originally planned. A picture of the current setup is included below, and hopefully I'll have it all working soon.