How about Transferring the LilyPad MP3 PCB to Flex. I can hardly imagine a Place in / on a Shirt or Hoodie were a rigid disk, with a Diameter of nearly 7 cm, could be placed without bother the Wearer.
I know the PCB has more Layers, but with its flexibility it should be doable, maybe with a bigger Surface-area or modular… Maybe even as a Hybrid (more Mashup) PCB / FLEX.
Greetings from Bavaria. P.S.: English is not my native language.