This is my version of a fan shroud for the E3D Aero.I could not find any designs that I was satisfied with, so this is the result. It is based on this design:
My design features a higher flow shroud that does not restrict air flow. It is also easy to print for a machine that does not yet have a fan shroud. I printed it with supports on that only touch the print bed (there are plugs for the hotend air ducts so the slicer does not build support material inside the shroud. They are easy to remove once the print is complete). I hope this helps.