40mm fan adapter for 50mm radial fan

This is a fan duct so I can use my 40mm fan with the cii cooler (http://www.thingiverse.com/thing:2004629), which is designed for a 50mm radial fan.

It's an adaption of my previous duct (http://www.thingiverse.com/thing:2225321), and fitted better at first printing, despite it cracking my too-brittle cooler (which I'll re-print properly if the cooler works out for my machine).

Fan plate source code from http://www.thingiverse.com/thing:735038

Please note that the adapter should be used