With the printrbot 1405 maker's edition, I don't know if I missed something or not, but the Fan Shroud they linked to in the instructions was for the wrong kind of printer. It was for the Printrbot metal, and didn't fit on the Simple. I couldn't find any others on Thingiverse that worked with the fan that came on the kit, so I made my own. With the few prints I've done with it so far, I've seen a noticeable difference in how smooth the layers come out. I might modify it at some point to turn at the end in order to direct the air more clearly at the nozzle, but for now it seems to be working fine.
I printed it with 5% infill, .2 Resolution, and 3 shells using PLA.
It fits on the Printrbot Simple bed, so you can print one out, using the Printrbot. Using the screws they provided for the fan, just place the shroud in front of it, with the flat side on top, and screw it back in.