I wore this LED T-Shirt under nice white shirt to teach the class at Hawaii STEM Conference.
It is an 8x10 array of individually addressable LEDs (HL1606 strip from +Adafruit Industries ) driven by PJRC Teensy 2.0 and 4 D-cell batteries, with a Pololu Step-Down Voltage Regulator D15V70F5S3 to keep it at 5vdc. Current code is the Basic Pattern sketch from example lib, with mod from AdaVision's Processing script to deal with zig-zag wiring. The PWM lib mod works too, but there were more examples for this. Adding other effects (like a beating heart, or other animations) is simple matter of programming. Comms & sensors would be cool too... someday.