This is my first 3D OpenScad design, so please be kind. This is a modified version of the hot end fan by Johann Rocholl. The Mini Kossel master zip file can be found at https://github.com/jcrocholl/kossel
It has been specifically sized for a J-Head hot end.
I added a 30mm fan with a duct to blow cool air across the printing part. I have uploaded to OpenScad design file in the hopes that someone can improve on it.
You will need a 40mm and 30mm 12V fan to fully appreciate the cooling. M3 screws are used to hold the fans in place. The 40mm fan is on all the time and in my setup is connected to the 12V Aux connection of the RAMPS board. The 30mm fan is connected to D9 to provide cooling to the part.