As soon as I saw the original item I thought - hey I could hang some stuff off that! So I did - the stuff in this case being a power switch and 5mm LED indicator. I also plan to mount a small LCD on it as well in the future.
I had to modify the original significantly as the holes for the threaded bars weren't even close to mine. I modded the design to fit the standard Printrbot base measurements for the threaded rods - not sure what the original author was basing his off.
Download, modify to your liking for your particular switch and indicator, print, install!