40 mm fan guard/guide

This is a remix of NeverDun's fan guard, he made a design that actually optimizes air flow and protects the fan blades. I made a version with a couple of air flow tricks.
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It is now printable without support
2 shells
3-10% infill

video of it running is here;
https://www.youtube.com/watch?v=ssyXqWaOjxo
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Original article here:
http://open3dp.me.washington.edu/2014/11/flashforge-creator-x-reducing-mass-improving-build-quality/

The SCAD version in only 40mm frie