A strong printed replacement for the folded Ultimaker fanduct. If your fanduct unfolds by itself, then this is a suitable replacement.It's best to print it on the backside, instead of the default orientation.
I have recommended this duct a few times. Daid I suggest you add the word "duct" to tags because when I searched for "duct" I didn't get this.
Caution regarding this duct:
http://umforum.ultimaker.com/index.php?/topic/3169-overhangs-sag-too-much/?p=23703