This is a enhancement/alteration of the already nicely designed Fan Shroud from "lampmaker" (http://www.thingiverse.com/thing:9515).
As suggested by Wim de Groot I added some diagonal studs to make the bridgegap smaller and the thing easier to print.
I also made to air outlet pointing towards (and right underneath) the extruder head. So the extruder should stay hot and the printed parts will cool down faster.
Ideas welcome, as I can implement them in a version 3.x.
I made mine with the current Sprinter Firmware and the "Failsafe" Profile with 90% infill.