This is a filament guide I made and am currently using for my Printrbot SimpleBeta. It works great! I've uploaded the .stl and the Inventor part file (.ipt) so those who have inventor can modify it for their needs.

Print Info:
Printed on - Printrbot Simple
Infill - .15
Speed - 10 mm/s
Bridging Speed - 60 mm/s
Temp - 180F
Layer Height - 0.3175

Enjoy!