I've slowly but surely been working on an Arduino-based trivia buzzer system (think Jeopardy). The handheld buzzers are made from 3/4" thin-walled PVC, and the wires for the switch and LEDs are connected to a keystone jack, which is at the bottom of the buzzer. Credit to jsadusk for the keystone mounting plate (http://www.thingiverse.com/thing:6647), which I added to an endcap I designed in OpenSCAD (file included). For best results, flip the model 180 degrees about the X or Y axis so the flat part prints down. The keystone jack I'm using is a CAT 3 one from Home Depot, which just barely fits into the shaft of the PVC pipe. Marked as a work in progress because I still want to round off the edges at the top and bottom, and because my OpenSCAD code is very sloppy. But as you can see, it does work. I included a version that was fixed (keystone_pvc_fixed.stl) for it being non-manifold, though the original file sliced and printed fine on my Printrbot. You may need to cut or sand the inner edges of the keystone mounting plate to get the keystone jack in. I had to for mine, but my Printrbot isn't calibrated quite as precisely as I'd like.