This was inspired by my earlier guitar pickup: http://www.thingiverse.com/thing:457172. It is built for my 4" (103mm) diameter sound hole. If you are interested in modifying for a different size, the Fusion 360 file is here: http://a360.co/1MgR28M Check out the video of it in action: http://youtu.be/2kegVcVyiukI printed this on a Replicator 2 at .15mm layer height with structures ON. For the electronics you will need a 1" (25mm) piezo speaker and a shielded 1/4" TRS guitar cable. Strip the ends of the cable. On one end connect the signal wire to the center of the Piezo element and the ground/shielding to the metal/brass surface of the piezo element. Connect the signal wire to the signal tab on the 1/4 in audio jack and connect the shielding to the ground tab.