Louvered fan cover

This is a derivative of so many Thingiverse things, I apologise if I miss crediting anyone. It is based on garycrowsellsr's fan guard (http://www.thingiverse.com/thing:26040) with an inspired addition prompted by nameless911 cardboard fan cover (http://www.thingiverse.com/thing:32660).

The cardboard cover is so efficient at redirecting the air away from the build platform that it means I could run my platform 10 degrees lower without the print edges lifting. But, being cardboard, it wasn'