I really liked thejim's solution (http://www.thingiverse.com/thing:40101), but i figured i could lasercut a very similar solution and keep the printrbot jr. looking more consistent. Here are the files. I was able to use the lasercutter at the Baltimore Hackerspace. I also recut all of my wood panels, minus the extruder, in acrylic because it looks cool. I imported the dxf into the redlaser software and cut it. it took several passes. I used acrylic I bought at home depot. i had to sand one of the shafts a bit to get it to slide into the new acrylic holes.