This is a fan duct to mount a fan on the K40 laser cutter head.
It is designed for a 40mm standard fan.
The picture looks ugly but I had to face an issue with the Y belt during the print. Anyway the piece is functional.
Thanks to d4d13 for the initial idea ;)
I used Sketchup 8 with "Export STL" plugin.
Not really happy to work with Sketchup due to its strange behavior but I needed to create this piece quickly.
The sketchup file is provided