Version 2, of my Fan Ducts. Designed to suit the "Olsson Block" (it can be used with the standard print head, just remove 3mm from the top of the Boss and Latch). UPDATE "V2 R" are a removable set (they just slip off) and a small fan stow part has been added.If using dual nozzles just print a mirrored version of the Left Hand Fan Duct.The Ducts do not require any fasteners to attach or for the fans, they swivel out of the way to allow easy access to the nozzle, and are vertically adjustable allowing adjustment for nozzle differences in set up. They also fit if using my Rear Heat Sink Fan Duct on the Rear Fan. https://www.youmagine.com/designs/print-head-bottom-modification, link to a modified Print Head Bottom piece to allow the cables to exit and the Heat Sink Fan DuctPrint Settings; for Cura. 0.1mm Layer, height, 1.2mm wall thickness, 20% fill, with Brim and Support everywhere. I would surgest printing in the orientation with the duct outlets being flat on the build plate.After printing remove designed support for the rear boss (Shown in Red) and all support structure, clean up any bits, clean out the rear boss with a 3.0mm drill.The height spacers are printed together on a sprig just seperate to use.Fitting. Remove existing fan duct and unscrew fans, Remove one rear print head screw at a time (Long Knurled Print Head assembly screw), add a 'Top Screw Spacer' and reassemble passing through the 'Fan Duct' Boss. Repeat for other side Duct. Fit a Top Screw Spacer to the front screws as well.The Fans are a push fit into the ducts.Height adjustment, The Ducts can slide up and down a few mm on the rear screws to allow for vertical adjustment, the latching provides enough friction to hold in place, printing of the spacer set will give you spacer 0.5mm, 1mm &  2mm thick, these slip onto the rear screw below the duct and allow repeatability of position.Please remember to latch the ducts back into position after any adjustments have been made before “HOME HEAD”There is a great improvement on air flow so you may need to reduce the percentage flow depending on your heater. If you are running the “Olsson Block” there is a 35W heater available from “3Dsolex” What Duck? Designs hope you enjoy this design, it was inspired by "Ultimaker 2 single -and Dual-Head Fan Cages (CPv9)" by mnis, with the screwless fan mounts and swivel feature.Please let me know how you get on using these Ducts and any comments etc. this 2nd version has improvements due to suggestions and requests. Izzy18/12/2015 UPDATEThere is now a easily removable set the "V2R" along with a "fan stow"After warping the bottom edge of the duct when printing with a bed temperature of 100 Degrees and zero fans, i've redesigned the back boss to a C so that it can be slipped off when not needed, the "Fan stow" can be printed normal and mirrored to hold the fans in a stored position when the ducts are removed if printing with 0 fans. It takes less than 60 seconds to remove the ducts,  remove the fans, fit the Fan Stow parts and slip in the fans. and the same to reinstall the ducts. so no great effort.21/12/2015 UPDATESlight alteration to all Tabs to slightly increase friction, if too tight gently file away material to suit.Added new version "V2F" has fixing mounts to match the original screw holes on the print head, it can be used with or without fixing screws if wanted.