I couldn't find any good side fan mounts that were simple to print for the Printrbot Jr., so I made my own. No extra parts needed in order to attach to printer. It will attach using the existing screws that came with the printer. Fits snug and works great.
I printed using .35 mm thickness and .2 infill and it came out great. If you print PLA and ABS make sure that you print this with ABS so that it will withstand the heat from the extruder.