At the request of Robscar (http://www.thingiverse.com/robscar/about) I modified my E3D fan duct (http://www.thingiverse.com/thing:494430) to fit his bracket system for his K8200 printer (http://www.thingiverse.com/thing:808238). It was a minor change in the duct mountings. I also modified his bracket slightly to potentially provide a bit snugger fit.
I hope this works for you and expands the number of systems on which this duct can be used. I think this modification makes the design a bit more generic.
UPDATE: In response to numerous requests to make several significant changes to the design, I've updated the 40mm duct and moved the mounting to a modified 30mm E3D shroud. The updated design can be found at: http://www.thingiverse.com/thing:1165614. This adds magnetic couplers and makes assembly and removal of the ducts a simple matter of pressing parts together. I've tested the hold and all parts fit snuggly and hold well. I've had my printer testing this redesign for over a month and there have been no failures. Both fans hold very firmly in place while still being easy to assemble.
Please feel free to make requests / suggestions.